[F91] Users Guide Volume 1

CAD package for electromagnetic and thermal analysis using finite elements

FLUX® 9.10

User’s guide

volume 1

General tools Geometry and mesh

Copyright – March 2005

FLUX software : Copyright CEDRAT/INPG/CNRS/EDF CAOBIBS software : Copyright ECL/CEDRAT/CNRS/INPG FLUX documentation : Copyright CEDRAT

FLUX’s Quality Assessment 2D Application : Electricité de France, registered number AQMIL002 3D Application : Electricité de France, registered number AQMIL013

This user’s guide was published on 17 March 2005

Ref. :

K101-910-EN-03/05

CEDRAT 15, Chemin de Malacher - Zirst

38246 MEYLAN Cedex France

Phone: +33 (0)4.76.90.50.45 Fax: +33 (0)4.56.38.08.30

Email : [email protected]

Web : http://www.cedrat.com

FLUX® 9.10 TABLE OF CONTENTS VOLUME 1

TABLE OF CONTENTS

FLUX (2D and 3D applications) Volume 1 : General tools

Geometry and mesh Volume 2 : Physical description, Circuit coupling,

Kinematic coupling Volume 3 : Physical applications:

Magnetic, Electric, Thermal, …

FLUX 2D application Volume 4 : Solving and results post-processing

FLUX 3D application Volume 4 : General tools (3D environment)

Solving and results post-processing Volume 5 : Physical applications

(complements for advanced user)

USER'S GUIDE PAGE A

TABLE OF CONTENTS VOLUME 1 FLUX® 9.10

PAGE B USER'S GUIDE

FLUX® 9.10 TABLE OF CONTENTS VOLUME 1

TABLE OF CONTENTS VOLUME 1

1. Supervisor .................................................................................................................. 1 1.1. General presentation .................................................................................................3 1.2. The FLUX modules ..................................................................................................11 1.3. Standard or user version .........................................................................................25 1.4. File compression and archive management............................................................37 1.5. Additional tools and options.....................................................................................43

2. Environment and graphic representation.................................................................. 49 2.1. Working environment: role of different zones ..........................................................51 2.2. Graphic representation: a matter of viewpoint.........................................................57

3. FLUX project and FLUX object management........................................................... 65 3.1. FLUX Project............................................................................................................67 3.2. FLUX Object ............................................................................................................71

4. General operation: data management...................................................................... 75 4.1. Concepts of entity and manipulation of entities .......................................................77 4.2. Selection of entities..................................................................................................83 4.3. Data handling...........................................................................................................93 4.4. Visualization of entities ............................................................................................99

5. Command file, Python language ............................................................................ 103 5.1. To begin .................................................................................................................105 5.2. FLUX and Python language...................................................................................109 5.3. Examples of command files ...................................................................................115

USER'S GUIDE PAGE C

TABLE OF CONTENTS VOLUME 1 FLUX® 9.10

6. Geometry: principles ...............................................................................................123 6.1. Modeling strategies ................................................................................................125 6.2. Study domain .........................................................................................................129 6.3. Characteristics of geometry building module.........................................................141 6.4. Tools of geometry building module ........................................................................151 6.5. Geometry building: general steps ..........................................................................155

7. Mesh: principles ......................................................................................................159 7.1. Mesh algorithms and field calculations: general points .........................................161 7.2. Mesh strategies: mixed mesh or automatic mesh .................................................169 7.3. Operation of the Mesh module: general steps.......................................................175 7.4. Mesh generators specificities and limitations ........................................................181 7.5. Description of specific meshes, examples.............................................................191

8. Geometry/mesh importation: principles...................................................................203 8.1. Geometry/mesh importation: overview ..................................................................205 8.2. Geometry importation (IGES, STEP, DXF, STL, FBD, INTER

formats) ..................................................................................................................210 8.3. Mesh importation (NASTRAN, PATRAN, UNV Ideas formats) .............................220

PAGE D USER'S GUIDE

FLUX® 9.10 Supervisor

1. Supervisor

Introduction This chapter presents the FLUX Supervisor

Contents This chapter contains the following topics:

• General presentation • The FLUX modules • Standard or user version • File compression and archive management • Additional tools and options

USER'S GUIDE PAGE 1

Supervisor FLUX® 9.10

PAGE 2 USER'S GUIDE


1.1. General presentation

Introduction This section describes the FLUX Supervisor, with which you can run FLUX

modules and manage your FLUX project files and directories.

Contents This section contains the following topics:

• Start the FLUX • Appearance of the FLUX supervisor: Display menu • My programs

USER'S GUIDE PAGE 3


1.1.1. Start the FLUX supervisor

Start the FLUX supervisor

To start the FLUX supervisor from the Windows taskbar, proceed as follows:

Step Action

1 Click Start > Programs > Cedrat (or your installation directory) > FLUX_9.10

The Supervisor Window

The FLUX Supervisor window is divided into several areas. These different areas are identified in the following figure, and then detailed in the following blocks.

Menu bar

Tool bar

Program manager

My programs

Project files

Flux view (2D only)

Directory manager

Continued on next page

PAGE 4 USER'S GUIDE


Parts of the Supervisor

The different parts of the FLUX Supervisor and their functions are presented in the table below.

Part Function

Menu bar Windows commands for FLUX • File • Display • Versions • Tools • Help

Tool bar

Icons for common tasks in FLUX • User version • Compress/Decompress a project • Options (memory, license, etc.) • Help (link to online Users Guide for FLUX)

Program manager Displays the FLUX modules The different modules are grouped by “family” in different folders. Each module is shown as an item in the tree.

You can expand a folder by clicking on the sign.

You can start a module by double-clicking on its name, e.g., Geometry.

My programs

Links to other programs, such as: • DOS Shell • Windows Explorer You can add links to other programs here, as you wish.


USER'S GUIDE PAGE 5


Parts of the Supervisor (continued)

Part Function Directory manager Displays the computer’s directory.

Files Displays project files.

FLUX View

Displays: • the model geometry for the selected 2D

project file (*.TRA) • the FLUX View logo, if no problem is

selected

PAGE 6 USER'S GUIDE


1.1.2. Appearance of the FLUX supervisor: Display menu

Introduction You can change the appearance of the FLUX Supervisor screen, e.g.:

• show or hide parts of the FLUX Supervisor • resize or move parts of the FLUX Supervisor

Displaying different parts of the FLUX supervisor

The following figure illustrates the parts of the FLUX Supervisor window that are affected by the Display commands: • the Tool bar • the Program manager • the Geometry view (for FLUX2D)

Geometry view

Tool bar

Program manager

Move parts of the FLUX supervisor

To move one of the FLUX supervisor parts: Use the specific resizing handle.


USER'S GUIDE PAGE 7


Show/hide FLUX supervisor parts

To show or hide parts of the FLUX Supervisor:

Step Action 1 Click the Display menu

2 Choose the parts you want to display on your screen.

A check mark ( ) indicates that an option is selected or active. You can cancel the display of these three areas by clicking on the check mark to remove it.

Effect on the supervisor: example

The following figure shows the Supervisor when Display geometry is not selected:

PAGE 8 USER'S GUIDE


1.1.3. My programs

Principle In the My programs area, you will find links to two programs:

• Windows Explorer • DOS window You can add or remove links to other programs.

Add a program To add a program, use the context menu (right click in the concerned zone)

Step Action 1 Click Add a program ... 2 Select the program to add

Remove a program

To remove a program, use the context menu (right click in the concerned zone)

Step Action

1 Select the program to delete 2 Click Delete …

USER'S GUIDE PAGE 9


PAGE 10 USER'S GUIDE


1.2. The FLUX modules

Introduction This section describes the FLUX (2D, 3D or Skewed) module area, which

contains links/commands to run FLUX (2D, 3D or Skewed) modules.


• The program manager area: overview • FLUX2D modules • FLUX3D modules • FLUXSkewed modules • Authorized modules

USER'S GUIDE PAGE 11


1.2.1. The program manager area: overview

Contents of the program manager area

The program manager area of the FLUX Supervisor contains folders (in the form of a tree structure) in which you can find each of the main modules of FLUX (2D, 3D or Skewed). Select FLUX2D, FLUX3D or FLUXSkewed by clicking on one of the tabs at the bottom of the Program manager.

The following figures show the program manager areas for FLUX2D, FLUX3D and FLUXSkewed:

FLUX2D module folders

The FLUX2D module folders are described below:

Part Function Construction • Create a geometric model, mesh, electrical circuit, and

materials • Assign material and source properties to different

components, to assign boundary conditions, link an external circuit, etc.

Solving process Solve a problem (direct or batch mode) Analysis Compute various quantities, create displays and

animations of results Compatibility Settings for use with modules from previous FLUX

versions




FLUX3D and FLUXSkewed module folders

The FLUX3D and FLUXSkewed module folders are described below:

Part Function Construction • Create a geometric model, mesh, electrical circuit, and

materials • Assign material and source properties to different

components and boundary conditions, link an external circuit, etc.

Solving process, Analysis

• Solve a problem (direct or batch mode) • Compute various quantities, create displays and

animations of results Compatibility Settings for use with modules from previous FLUX

versions

Contents of the module folders

When you expand the folders, you will see icons and labels representing the FLUX modules (2D, 3D or Skewed) contained in the folder.



1.2.2. FLUX2D modules

FLUX2D modules: details

The FLUX2D modules are shown in the following figure:

Construction The Construction folder comprises the following modules:

Part Function Geometry & Physics

• Construct a geometric model and mesh • Create and assign physical and material properties to

components of a modeled device Circuit Draw and define electric circuits Materials database Add material models to the database




Solving process The Solving process folder comprises the following modules:

Part Function Direct Solve a model (perform the FEM calculations) in

interactive mode (the user can see the progress of the calculation on screen and if necessary, stop the calculation)

Batch Solve a model in batch mode (e.g., to reduce computation time for complex models)

Transient start-up Solve a model beginning with results from a previous solution (e.g., with a modified time step)

Stop solve Stop a calculation before it is completed Delete results Delete results from a previous calculation Convert results Convert results from versions older than 7.50 Metal 7 Start Metal 7 (metallurgical calculations)

Analysis The Analysis folder comprises the following modules:

Part Function Results Display results, create animations, etc. Coupling Create new FLUX2D problems from extracted values

(e.g., create a thermal problem from a magnetic application using the power density as thermal source)

Compatibility The Compatibility folder is divided into:

• Geometry Compatibility • Physical Compatibility • Analysis Compatibilité




Geometry Compatibility

The Geometry Compatibility folder comprises the following modules:

Part Function

Geometry with Preflu_2D

Construct a geometric model and mesh with Preflu_2D (the pre-processor from FLUX2D Version 7.6).

Geometry with Preflu

Construct a geometric model and mesh with Preflu (the original pre-processor from FLUX2D).

SPEED converter

Convert a geometry created with SPEED software into a *.FLU file.

Iges with Inter

Open the INTER program, a geometric file-conversion utility. For example, Inter will convert AutoCAD files into FLUX geometry files (and vice versa).

Flux3D Convertor

Convert the files preceding the 8.10 version

Physical Compatibility

The Physical Compatibility folder comprises the following modules:

Part Function

Create Create and assign physical and material properties to components of a modelled device

Modify Modify physical properties, e.g., to create multiple cases using the same geometry and mesh but with varying physical properties

Copy Copy physical properties, e.g., to create multiple cases using the same physical properties but with different geometry or mesh models

Circuit with Cirflu

Draw and define electric circuits with Cirflu (circuit tool from previous FLUX versions)

Analysis Compatibility

The Analysis Compatibility folder comprises the following modules:

Part Function

Solve with Resgen

Solve a model in interactive mode with Resgen (the original solver from FLUX2D).

Result with Expgen

Analyse results with Expgen (the original Postprocessor from FLUX2D).

Draw Open the drawing and plotting utility from previous FLUX versions.

Solve with FLUX3D_2D

Solve a problem with the 2D solver of FLUX3D



1.2.3. FLUX3D modules

FLUX3D modules: details

The FLUX3D modules are represented in the following figure:





Physical, Solving process, Analysis

The Physical, Solving process, Analysis folder comprises the following modules:

Part Function

FLUX3D Work with FLUX3D Solve in batch Solve a model in batch mode (e.g., to reduce computation

time for complex models) Stop the solving process

Stop a calculation before it is completed




Compatibility The Compatibility folder comprises the following modules:

Part Function Circuit with Cirflu


Iges with Inter Open the INTER program, a geometric file-conversion utility. For example, Inter will convert AutoCAD files into FLUX geometry files (and vice versa).


Flux3D Convertor




1.2.4. FLUXSkewed modules

FLUXSkewed modules: details

The FLUXSkewed modules are represented in the following figure:





Physical, Solving process, Analysis

The Physical, Solving process, Analysis folder comprises the following modules:

Part Function

FLUXSkewed Work with FLUXSkewed Solve in batch Solve a model in batch mode (e.g., to reduce computation

time for complex models) Stop the solving process

Stop a calculation before it is completed




Compatibility The Compatibility folder comprises the following modules:

Part Function Circuit with Cirflu


Iges with Inter Open the INTER program, a geometric file-conversion utility. For example, Inter will convert AutoCAD files into FLUX geometry files (and vice versa).


Flux3D Convertor




1.2.5. Open a module

Open a module To open a module:

• Double click the module name in the data tree.

Open a module with a selected project file

See § “General options: language, memory, database” If you want to open a module and a selected project at the same time:

• In the Tools menu, click Options or click the Options icon

• Select the General tab • Under Other at the bottom of the dialog, check the box next to Open the

program with the selected project



1.2.6. Authorized modules

Introduction Authorized modules are the modules installed on your PC.

Check authorized modules

To check authorized modules: • In the Tools menu, click Authorized Module • In the Protection Tool Box, select your protection tool

(Key authorization or Flexlm authorization)

See the specific cases (Key authorization or Flexlm authorization) explained below.




Key authorization

When you click the Key authorization button in the Protection tool dialog, the following dialog opens:

• Click the desired tab (FLUX2D, FLUX3D, …) • Click the Read Key button to see the authorizations for your license.

This dialog shows all modules and options that are included in your license.

Warning DO not make any changes in the Key state dialog, or you may invalidate your

license. If you are having any problems with your license, you should call your distributor for help.




Flexlm authorization

When you click the Flexlm authorization button in the Protection tool dialog, the following dialog opens:

• Click the Lire Licence button to open the licence file • Click the Flux2d or Flux3d button to read the authorizations for your

license.

Warning Do not make any changes through this dialog, or you may invalidate your

license. If you are having any problems with your license, you should call your distributor for help.



1.3. Standard or user version

Introduction This section presents information about selecting and managing user versions

of FLUX2D or FLUX3D.

The Standard version is selected by default.

A user version is a version that extends the software’s basic modelling capabilities.

For example, with a user version you can define non-standard physical properties (voltage or current source, material characteristics, etc.) as a function of criteria you choose yourself (time, space, variable, etc.).


• Concept of a user version • Choose the working version • The User version manager • Edit a user version • Create a new user version • Modify a user version • Delete a user version • Options

Notes on what to read

In the chapter entitled « User sub routines » (for FLUX2D and FLUX3D, respectively) you will find information pertaining to: • description of the user versions included with the software • available possibilities of user versions : choice and writing of user

subroutines, etc.



1.3.1. Concept of a user version

FLUX versions There are two separate versions of FLUX2D or 3D:

• standard version • user versions

User version: definition

A user version of FLUX (2D or 3D) is a version that extends the software’s basic modeling capabilities.

User version: structure

From the point of view of its structure, a user version is a version that includes both: • the standard version of FLUX2D or 3D ; and • a specified number of user subroutines.

Default location for user versions

User versions are located by default in the following directories: • C:\Cedrat\User\user2d for 2D user versions • C:\Cedrat\User\user3d for 3D user versions

User versions included with the software

Predefined user versions are included with the FLUX software. These are listed in the following table:

User version Function

Brushlike_81.f2d switch depending on position (version 8.1) Table_81.f2d read of properties (materials, sources) in a file

(version 8.1) Lamination_810A.f3d taking into account the lamination of a material

without defining the geometry of the sheets

Documentation on user versions

Informations about user versions included with the FLUX software are available in the following directories: C:\Cedrat\User\user2d (table_readme.pdf) C:\Cedrat\User\user3d (lamination_readme.pdf)



1.3.2. Choose the working version

Standard version

By default you will be working with the standard version of FLUX2D or FLUX3D. To work with a user version, you must specify the desired user version in the FLUX Supervisor.

Choose the working version

To choose a version (standard or user): • In the Versions menu, click the desired version.

The user versions included with FLUX2D and FLUX3D are shown in the following figures.

FLUX2D:

FLUX3D:

Result: The name of the user version is displayed in the title bar of the program manager.



1.3.3. The User version manager

Introduction The available user versions are listed in the Versions menu.

You can edit a predefined user version, create new user versions, and modify or delete user versions.

The various operations to manage user versions are performed through the User version manager.

Open the User version manager

To open the User version manager:

• In the Tools menu, click User version or on the icon

The User version manager

The User version manager is shown in the following figure

Location of the directory containing the user version files

Tool bar (shortcuts to the main functions: create, delete, compile user version, etc.)

Name of the user version

Names of the subroutines included in the user version

Date of compilation FLUX version number




The mode area function

In the Mode area, you can select the location of the directory for the user versions.

The two main locations are shown in the following table:

Mode Disk location Local Defined by the user

(Version tab, Options icon) Shared Default directory:

• C:\Cedrat\User\user2d for 2D user versions • C:\Cedrat\User\user3d for 3D user versions

The User version toolbar

The user version toolbar provides shortcuts to the most common functions to work with user versions. The icons and their functions are explained in the following figure:

Create a new user version

Add sub-routines

Edit the subroutine

Delete the current user version

Delete the subroutine

Compile the current user version

Display the options

Display the online documen-tation



1.3.4. Edit a user version

Edit a user version

To edit a user version:

Step Action

1 Open the User version manager with the icon

2 In the Name field, choose the name of the user version to edit 3 Click OK to close the User version manager

Example The following figure shows information about a user version:

• The name of this version is brushlike.f2d_usr. • There are 2 subroutines included in this particular user version:

usrmag.f and usrswc.f. • The Compilation report for this user version indicates that it was compiled

on 12 May 2004 for Flux Version 8.1.



1.3.5. Create a new user version

Introduction This section describes the creation and management of new user versions.

You should read the part concerning “User subroutines” (FLUX2D and FLUX3D, respectively) before beginning this section.

Note In order to create a user version, you must have a Digital Visual Fortran

compiler (Version 5 or 6) installed on your computer.

Create a user version

The different steps in the creation of a user version are shown in the following table and detailed in the following sections:

Step Action

1 (optional)

Define the directory location for the new user version (for the Local option)

2 Create the new version: • Choose a name • Load the reference files that will serve as a basis for

writing the user subroutines 3 Write the user subroutine(s) 4 Compile the new user version

Step 1: Define the directory location for the new user version

If you want to choose the directory in which to place the new user version (operating in Local mode):

Step Action 1 In the Tools menu, click Options or click the icon

2 Choose the User version tab 3 In the field Flux2D user version directory (for the local mode)

or in the field Flux3D user version directory (for the local mode), enter the name of the directory in which to place the new user version




Step 2: Create the new user version

To create the new version, proceed as follows:

Step Action 1 In the User version manager:

• Click on the icon The New user version dialog is open

2 Choose a name for your user version: • Type a name in the Name field

3 Add user subroutines: • Click the Add button and select the user subroutines you want to

add to your new user version 4 Close the New user version dialog:

• Click OK to validate the creation

At the end of this step, a directory with the name of the new user version is created. It contains the reference files (*.f) which serve as the basis for writing the user subroutines.

Step 3: Write the user subroutine

See the documentation concerned the writing of user subroutines in the user’s guide: • chapter 7 volume 3 for FLUX3D • chapter 3 volume 4 for FLUX2D



Step 4: Compile

To compile the version:

Step Action

1 In the User version manager:

• Click on the icon The following message is open:

Information concerning the progress of the compilation is displayed in the Compilation report area of the User version manager.



1.3.6. Modify a user version

The changes you can make

These are the modifications you can make to a current user version: • Add user subroutines • Remove user subroutines from the current version (saving them in the

designated directory without compiling them with the current version) • Delete user subroutines from the current version

Modify a user version

To modify a user version (add or delete user subroutines), in the User version manager, proceed as follows :

Step Action

1 Choose the name of the user version you want to modify 2 In the User version manager:

To Add a subroutine:

• Click on the icon and select the user subroutines you want to add

To Remove a subroutine: • Click to remove the checkmark in front of the name of the user

subroutine To Delete a subroutine:

• Select the user subroutine you want to delete

• Click on the icon 3 Modify the subroutine files 4 Compile the user version



1.3.7. Delete a user version

Delete a user version

To delete a user version, proceed as follows:

Step Action

1 In the User version manager: • Choose the name of the user version you want to delete

2 In the User version toolbar:

• Click on the icon The following message is open:

3 Confirm the deletion:

• Click on the Yes button The user version is removed



1.3.8. Options

Access the Options dialog

To access the Options dialog:

• In the Tools menu, click Options or on the icon

User version options: overview

When you click the User version tab in the Options dialogue, you will see the following:

Parts of the User version tab

The User version tab is divided into the following areas, as shown in the previous figure.

Part Function

User version Choose the: • editor for the *.f files • directory for user version (in local mode)

Compiler Choose the version of the Digital FORTRAN compiler



1.4. File compression and archive management

Introduction This section presents information about file compression and archive

management.


• Archive concepts • Archive manager • Create an archive • Restore an archive



1.4.1. Archive concepts

File compression: benefits

The files of a complete project may become large (for example, for a complex geometry, or a fine mesh; during a multi-solving process that generates a large number of result files, etc.).

Therefore, it may be helpful to compress these files to facilitate the transfer or storage of the project.

Archive file: contents

The archive file (*.tar.bz file) can contain various files: • the set of files comprising the entire project, or only specified files

(geometry description, etc.) • other files such as printing files (*.PRT), drawing files (*.DES), or others.

For archiving FLUX project files, several options are available as explained below.

FLUX2D options

FLUX2D options allow the user to choose the project files to be archived:

Option Files

Whole project Entire set of project files from the project Without results Project files without results

FLUX3D options

FLUX3D options allow the user to choose the project files to be archived:

Option Files

Whole project All files from the “*.FLU” directory: PROBLEM_FLU.PFL, GEOM_FLU.PFL, MESH_FLU.PFL, SOLVE_i_j

Without finite element solution

Problem description files only: PROBLEM_FLU.PFL, GEOM_FLU.PFL, MESH_FLU.PFL

Without mesh Problem description files without mesh: PROBLEM_FLU.PFL, GEOM_FLU.PFL



1.4.2. Archive manager

Introduction The various operations for managing archives (creation and restoration) are

carried out through the archive manager.

Open the Archive manager

To open the archive manager: • In the Tools menu, click Compression/Decompression of a project

or on the icon

The Archive manager

The Archive manager is shown in the following figure:



1.4.3. Create an archive

Creation of an archive

The creation of an archive follows the process outlined below:

Stage Description

Initialization The user must choose: • the project to compress (and the compression option) • the name of the archive file and its place on the disk

Creation The user must choose: • files to include in the archive file and • create the archive

Create a FLUX project archive

To create a FLUX project archive, proceed as follows:

Step Action 1 Click one of the following two icons:

• Create a FLUX2D project archive icon /

Create a FLUX3D project archive icon The Create a FLUX3D project archive dialog is shown:




Create a FLUX project archive (continued)

Step Action 2 Fill in the fields in the dialog window:

• Project name • Directory where the archive will be created • Archive name

3 Choose the compression options 4 Click on the Next Button The next dialog of the Create a FLUX3D project archive dialog is

open:

5 Add files to the archive file:

• Click the Add new files… button and select the files you want to add to the archive file.

6 Create the archive: • Click the Finish button

The following message is open:



1.4.4. Restore an archive

Restore an archive

To restore a FLUX project archive, proceed as follows:

Step Action

1 Click on the icon

The Restore an archive dialog is open:

2 Fill in the fields in the dialog window:

• Name of the file to be restored • Directory where the file will be restored

3 Restore the archive: • Click on the Restore button

The following message is open:



1.5. Additional tools and options

Introduction This section presents information regarding additional tools and options

available to the user.


• Online Help • Skin depth calculator • License options • General options: language, memory, database • Display options



1.5.1. Online Help

Access the online help

To access the online help:

• In the Help menu, click on Manual or on the icon

FLUX Online Help

When you click the Help icon, you are linked to the online version of the FLUX User’s guide.

Click any of the hyperlinks to open the corresponding section of the FLUX User’s Guide.



1.5.2. Skin depth calculator

Introduction In the Tools menu there is a calculator specifically for computing the skin

depth.

Display the skin depth calculator

To display the skin depth calculator: • In the Tools menu, click Skin depth…

Calculator for the skin depth computation

The skin depth calculator appears as shown below:

Calculate the skin depth

To calculate the skin depth: • In the Values area, fill in the fields: Resistivity, Relative permeability,

Frequency • In the Result area, choose the units (mm, etc.)



1.5.3. License options

Access the license options

To access the license options:

• In the Tools menu, click Options or on the icon

License options: overview

When you click the License tab in the Options dialogue, you will see the following:

License options: functionalities

Within the License tab, you can • Select or verify the type of license you have: Flexlm; Flexlm – key; or Key • For licenses using Flexlm, you can verify the location of your license file • See a list of the applications your license includes (see § Authorized

modules)



1.5.4. General options: language, memory, database

Access the general options

To access the general options:

• In the Tools menu click Options or on the icon

General options: overview

When you click the General tab in the Options dialogue, you will see the following:

General options: functionalities

Within the General options tab, you can: • Choose the language for your FLUX interface (English or French) • Manage the memory allocation for FLUX2D or FLUX3D • Choose the directory for the Materials database:

- Current directory: the database is named MATERI.DAT. - Shared: in directory Materials generally installed in the directory C:\Cedrat (default directory of the FLUX location) you can select a file named *MATERI.DAT. There is the predetermined database named FLUX_810_MATERI.DAT.

- Local • Have FLUX open a project whenever you open the FLUX program



1.5.5. Display options

To access the Display options

To access the Display options:

• In the Tools menu click Options or on the icon

Display options: overview

When you click the Display tab in the Options dialogue, you will see the following:

Display options: functionalities

Within the Display options tab, you can: • Choose options for the appearance of the “DOS modules”:

- Choose the background color for the graphics display. Black is the default background color, and for everyday work, you may prefer a black background. However, if you want to capture the graphics screen for presentations, for example, you may prefer a white background

- Set the number of lines for the console text. This setting controls how many lines are displayed in the “console” area

• Choose the operation mode for the SPEED software link. The Window mode displays the Preflux 2d module while SPEED is running, so you can see what is happening.


FLUX® 9.10 Environment and graphic representation

2. Environment and graphic representation

Introduction This chapter presents:

• working environment: description and role of different zones in FLUX window

• the different representations of devices in the graphic zone (graphic views).


• Working environment: role of different zones • Graphic representation: a matter of viewpoint

Reading advice All aspects related to the data organization, manipulation and display are

treated in the chapter “General functionality: data organization”


Environment and graphic representation FLUX® 9.10



2.1. Working environment: role of different zones

Introduction This section concerns the working environment i.e.:

• the description and role of different zones presented in the FLUX window • the customization possibilities proposed to the user


• Presentation of working environment • Modifying the environment



2.1.1. Presentation of working environment

FLUX window The general FLUX window consists of several zones. These different zones

are identified in the figure below.

Title bar

Menus bar

Data tree

Graphic scene

toolbars

Status bar

Context bar

Graphic scene

History

Menus toolbars

Configuration of the window

Preflux desktop is automatically depends of: • Dimension of the application (2D or 3D) • The physical application defined (no physic defined, magneto static,

electrostatic, …) • The context: Geometry, Mesh or Physic • Or sub context (sub context for healing the geometry…)




Role of zones The different zones and their principal roles are briefly described below:

Element Function Title bar General information:

• Software name, version number • Application (3D Transient Magnetic)• Project name

Menus bar

Access to the different menus: • Project, Application, View, Display,

Select

• Geometry, Mesh, Physics, Tools, Help

Context bar

Access to the toolbar corresponding to the contexts: • Geometry, Mesh, Physics

Menus Toolbars Project

Commands of Project menu: • New, Open…, Save, Close, Exit

Tools

Commands of Tools menu: • Undo

Contexts toolbars: Geometry Context Commands of Geometry context:

• Creation of the geometric entities

• Propagate / Extrude Line, Face …

• Build Faces, Volumes, Assign

Regions

• Measure geometry (distance

between two points …)

• Check of the geometry Mesh Context Commands of Mesh context:

• Creation of mesh entities

• Actions on the mesh • Check of the mesh

Physic Context Commands of Physic context:

• Creation of physic entities

• Actions on the physics • Check of the physics




Role of zones (continued)

Menus Toolbars (in the graphic scene): View Commands of the View menu:

• Refresh view, Zoom all, Zoom region

• Standard 1 view, Standard 2 view, Opposite

view, Direction of view, View on X, View on Y, View on Z, Four views mode

Display Commands of the Display menu: General

• Display of coordinate systems, points, lines, faces, volumes, surface regions, volume regions

in the Geometry context

• Display of surface elements, points numbers,

lines numbers in the Mesh context

• Display of mesh points, mesh lines, nodes,

surface elements in the Physic context

• Display of non meshed coils

Selection Commands of the Select menu:

• Activate the selection filter, Select points,

Select lines, Select faces, Select volumes, Select surface regions, Select volume regions




Role of zones (continued)

Element Function Entities tree

Entities tree of the FLUX project

History

Information concerning different current actions (project evolution): • Restoring of data during a project

opening, • Comments about the current

actions, • Advance of computation during the

solving process, … Zone Command (masked)*

Command echo

Command

Access to functioning mode by commands in Python language.

*This zone is masked. To display this zone, see § “Modifying the environment”.



2.1.2. Modifying the environment

Modify the background color

To modify the background color (reverse video): • in the View menu, click on Reverse video

Display/ mask zones

To display / mask zones: • use the arrows located on the zones sides

(see example in the block below)

Display the Python command zone

The zone for the commands in Python language is masked (by default). To display this zone: • click on the arrow located on the bottom of the history zone as shown in the

figure below.

Arrow to display the Python command zone

⇒



2.2. Graphic representation: a matter of viewpoint

Introduction This section concerns the graphic representation of the modeled device.

When referring to the graphic representation of a device, we are interested: • on one hand, in the different entities and their appearance: points and their

visibility, lines and their color, faces, surface elements…. • on the other hand, in the type of displayed view: side view, top view,

bottom view, global view, … in its position and dimensions in the graphic display zone.

The first aspect of the graphic representation (called visualization of entities) is treated in the chapter “General functionality: data organization”.

The second aspect (called viewpoint) is treated in this chapter.

This section presents the following: • graphic view and graphic viewpoint • possibilities to modify the view (displacement, rotation, zoom …) • presentation of predefined views (standard view, base planes views,

opposite view, memorized views ….)

Content This section contains the following topics:

• Concepts of view and viewpoint • Modifying the view • Predefined views • Four views



2.2.1. Concepts of view and viewpoint

The graphic window

The graphic window is a window where a graphic representation of the modeled device is displayed.

The coordinate system displayed in the left bottom of the window permits the orientation of the figure (system coordinate OXY for Preflux 2D, and system coordinate OXYZ for Preflux 3D).

2D or 3D representation of a device

The graphic representation of the device that is modeled is a plane representation (in a graphic window): • of a volume device (3D) for a Preflux 3D study • of a section in a volume device (3D) for a Preflux 2D study Thus, in 3D there are more graphic representations of the device : top view, laterally view, perspective view…

Concept of view The 2D or 3D view of a device in the graphic zone is called graphic view.

Concept of viewpoint

The graphic view is the image of the device visualized from a viewpoint. This concept is illustrated in the figure below.



2.2.2. Modifying the view

Options It is possible to:

• move the view (translation) • change the view (change the viewpoint) • adjust the view (enlarge or reduce a zone of the view)

How to modify a view

The modifications can be made: • using the mouse • using the commands of the View menu (or the corresponding icons) The different types of modifications (using the mouse and the correspondence with the commands of the View menu) are presented in the table below.

Modification Mouse Commands Icons

Displacement Right button - - Changing the point of view Left button Viewpoint Dimension Mouse wheel Zoom

Move a view (with the mouse)

To move a view (translate) in the graphic window: • Click on the view (with the right button of the mouse) • Drag the view at the new location, keeping pressed the right button.

Change the viewpoint (with the mouse)

To change the viewpoint (i.e. rotate the device): • Click on the view (with the left button of the mouse) • Rotate the view in the new position, keeping pressed the left button.

Resize a view (with the mouse)

To resize a view (i.e. reduce/enlarge the device): • Click on the graphic zone (with the left button of the mouse) • Reduce/Enlarge the view with the mouse wheel.




Change the viewpoint

To change the viewpoint:

Step Action

1 In the View menu: • click on View direction …

or on the icon 2 In the View direction box:

• enter the values: - x, y and z corresponding to the camera position - x, y and z corresponding to the target point position - rotation angle - zoom scale

Resize a view zone (zoom)

To resize (enlarge/reduce) a zone: • click on one of the Zoom commands in the View menu

(or on the corresponding icon of the Zoom toolbar)

The different available zooms are presented in the table below.

Zoom Icon all Total view

in - Enlarge the view out - Reduce the view

region This option allows the user to set with the mouse the rectangular zone to enlarge.



2.2.3. Predefined views

Options It is possible to choose one (more) view(s) from a list of predefined views:

• standard view n°1 and n°2 • views on the reference planes X, Y, Z • opposite view

Standard views The standard views n°1 and n° 2 are presented in the figures below.

Standard view 1 Standard view 2

Views on the reference planes

The views on the reference plans X, Y, Z are presented in the figures below.

Plane X Plane Z

Plane Y




Opposite view The opposite view is presented in the figure below

Standard view 1 Opposite view

Choose a predefined view

To choose a predefined view: • click on the desired view in the View menu.

The different predefined views (and their corresponding icons) are presented in the table below.

Point of view Icon

Standard view n°1 Standard view n°2

Opposite view

Plane X Plane Y Plane Z



2.2.4. Four views

Options The views on the reference planes X, Y, Z and also the standard view n°1 can

be displayed in four independent windows. Only one window is active (surrounded by a border of different color).

You can also display two windows from the four proposed.

Pass to 4 view mode

To pass to 4 views mode: • click on Four views mode in the View menu

or on the icon .

Change the number of views

To change the number of views: • Select the window or the two windows which you desire to preserve • Drag with the mouse a resizing handle until the window or the two

windows occupy the entire graphic zone.




FLUX® 9.10 FLUX project and FLUX object management

3. FLUX project and FLUX object management


• the concept of FLUX project and the commands of Project menu (New, Open, Save, Close)

• the concept of Flux object and the commands for object importation (Importation of FLUX object)

Content This chapter contains the following topics:

• FLUX Project • FLUX Object


FLUX project and FLUX object management FLUX® 9.10



3.1. FLUX Project

Introduction The user will find in this section the definition of a FLUX project, and the

description of commands of project management (New, Open, Save, Close).


• FLUX project and FLUX object management • Creation, opening and storage of projects



3.1.1. FLUX Project: definition, type of data storage

FLUX project: definition

A FLUX project is the data ensemble corresponding to a FLUX study.

Storage type From the storage point of view, a FLUX project consists in:

• a repertory, which includes the project name completed by the suffix “.FLU".

• a files ensemble, whose names are fixed and whose content is explained in the table below.

File name File content

PROBLEM_FLU.PFL general description of the problem GEOM_FLU.PFL visualization modes of the geometry MESH_FLU.PFL nodes of the mesh

FLUX3D features

For a FLUX3D study, the repertory corresponding to the project contains also a file(s) that contains the result(s).

File name File content

SOLVE_FLU.EFL or SOLVE_FLU_i.EFL

results of a static application or results of a transient or a parameterized application

The index i gives the information about the value of the time step or of the parameter.



3.1.2. Creation, opening and storage of projects

Project Menu These commands are available by Project menu or by Project toolbar.

The operation of these commands is briefly pointed out below.

Project Menu Project Toolbar

Create a new project

To create a new project, proceed as follows: • Click on New from the Project menu, or on the corresponding icon from

the Project toolbar.

Result: FLUX recovers many information from the database model, in order to build the proper database of the new project. The new project is temporarily named ANONYM.

The message displayed in the console bar is: Loading new project ... Creation ANONYM DOMAINE(DOMAINE1) cree. L'occurrence creee devient active. *** Nom de structure inconnu *** ... end loading new project

Open an existent project

To open an existent project, proceed as follows: • Click on Open from the Project menu, or on the corresponding icon from

the Project toolbar. • Select the existing project (file) from the Select FLUX project dialog box.

Result: When a project built with an old version is opening, FLUX performs the update of the database. The message displayed on console bar is: Loading project 'D:\FLUX\flux_bibli\problem\PREFLU2D_2' ... Debut de la lecture ... fin de la lecture Mise a niveau de la structure de donnees: F3D_3.37 ==> F3D_3.38 Mise a niveau de la structure de donnees: fusion base standard L'occurrence creee devient active. *** Nom de structure inconnu *** ... end loading project




Save as a project

To save as a project in progress: • Click on Save as … from the Project menu. • Enter the project name in the Select FLUX project FLUX dialog box.

Save a project in progress

To save a project in progress: Click on Save from the Project menu, or on the corresponding icon from the Project toolbar.

Close a project To close a project:

Click on Close from the Project menu, or on the corresponding icon from the Project toolbar.

Result: When a project is closing, storage of project will be automatically proposed to the user.

Preflux 2D features

The .TRA file is automatically created for the surface meshed regions.



3.2. FLUX Object

Introduction The user will find in this section the definition of a FLUX object, the

operation modes of FLUX objects and the use of the importation object command.


• FLUX Object: user guide • Importation of FLUX objects



3.2.1. FLUX Object: user guide

Overview Before begin the description of a device, it is possible to appear the following

question:

Portions of this device can be used for the modeling of others devices?

Basic idea If the answer is yes, the geometric building of a device can be considered as a

structure in lego.

Then, the general principle of construction is as follows: • Description of different pieces of the structure in the independent FLUX

projects (base lego or FLUX objects). • Construction of the complete device in a new FLUX project, by means of

already built bricks (FLUX objects).

Example Geometric construction of a motor performed with stator and rotor parts

already build.

Rotor object: rotor geometry (ROTOR.FLU project)

stator object : stator geometry (STATOR.FLU project)

New object: motor geometry (MOTOR.FLU project)

Main interest: bank of objects

This type of construction presents certain constraints, but also offers the possibility to realize a bank of objects used for different studies.



3.2.2. Importation of FLUX objects

Principle By importation of FLUX objects we understand incorporating a FLUX

object in the project in progress (new or existent project).

This operation can be realized in different modes. The user has the possibility to import the entirely FLUX object (all the entities) or to use the filters (selection of entities).

Import an object

To import an object, proceed as follows:

Step Action

1 From the Actions menu, click on Flux Import and click on Import FLUX object

2 In the Import FLUX object box: • choose the file name to import • choose the filter




FLUX® 9.10 General operation: data management

4. General operation: data management

Introduction A finite element project contains a great volume of data, diverse and

interrelated In terms of FLUX software, these data (coordinates of points, types of lines, …) are called entities and depend on project context (geometry, mesh, …).

This chapter presents the mode of general operation of FLUX software (independently of context), i.e.: • the general organization of data : concepts of entity and of entity type • the different selection modes • the general commands of entities manipulation (create, edit, modify, delete

of entities) • the tools of entities visualization (display and appearance of entities in the

graphic zone)

At the end of this chapter the user will find the elements for a better understanding of concepts related to FLUX database (logical distinction between data structure and data themselves, concepts of entities, characteristics of an entity, relations between entities, …).


• Concepts of entity and manipulation of entities • Selection of entities • Data handling • Visualization of entities

Reading advice This chapter presents the mode of general operation of FLUX software

(independently of context). For specific detail of geometry and mesh modules, refer to the corresponding chapters.


General operation: data management FLUX® 9.10



4.1. Concepts of entity and manipulation of entities


• Entity and manipulation of entity • Database structure • Properties sheet

Vocabulary: warning

In this section we use a “simple vocabulary” for the description of entities and their manipulation.

At the end of the chapter we will use for advanced users a technical vocabulary, currently used in the description of data structures.



4.1.1. Entity and manipulation of entity

General definition

An entity is an object of the database of a FLUX project.

It can be: • a point, a line, a coordinate system, in the geometry context • a point or a line mesh, in the mesh context • …

Manipulation of entities

The build of a FLUX project consists in the manipulation of entities.

The basic operations of entities manipulation are the following: Add, Edit, Modify or Delete an entity.

Warning • There are specific entities for each FLUX modules depending on the

context (geometry, mesh, …) • The actions of entities manipulation always follow the same scheme

independent of context.

Example The points and the lines are entities of geometry module. The mesh point and

mesh line are entities of mesh module.

The procedure to create a point or a mesh line (Add command) is similar in geometry module and mesh module.

Classification It is possible to distinguish two families of entities.

Denomination Identified by Function Example “abstract” entity Name given by

the user Building tool Coordinate

system, transformation, …

“specific” entity Number defined by the software

Graphic object Point, line, surface element



4.1.2. Database structure

Entity: definition

An entity is an object of the FLUX3D database: It can be a point, a line, a material, …

The entities are classified by the entity type: type “Point”, type “Line”, type “Material”, …

Structure An entity is defined or characterized by:

- a type - a number, and a name, eventually - characteristics - relations with other entities

Examples A point is characterized in the following manner:

POINT (10) =COORD (REP (RCA1) UVW (100, 200, 200))COO (0.1, 0.2, 0.2)COLOR (White)VISIBILITY (Visible)

Entity type number

Characteristics

The point n° 10 is defined by: • its coordinates in a local coordinate system (RCA1): x=100, y=200, z=200 • its coordinates in a global coordinate system: x = 0.1, y = 0.2, z = 0.2 • a color: white • a visibility (visible or invisible): visible

To know more At the end of this chapter the advanced user will find the elements for a better

understanding of concepts related to the FLUX database (logical distinction between data structure and data themselves, concepts of entities, of characteristics of an entity, of relations between entities, …).



4.1.3. Properties sheet

Properties sheet: content

Each entity has attached a properties sheet, which contains the following information: • the identifier of the entity (for the user): a name or a number • the type of entity: point, line, … • the specific characteristics of the entity

Properties sheet: overview

The properties sheet is presented in the form of a dialogue box that contains: • a title bar with the type of entity • a zone (optional) corresponding to the name and the associated comment • different tabs containing the specific characteristics of the entity • buttons to validate the information or to close the sheet

Example:

Properties sheet of point n°69

Different sheets (entities)

There are two families of entities (and consequently, two types of presentation of sheets): • the entities identified by a name given by the user (ex : a geometric

parameter, a transformation, a mesh generator …) • the entities identified by a number defined by the software

(ex : a point, a line, a volume element …)

These sheets are presented below.




Entities identified by a name

The properties sheet of entities identified by a name contains the following information: • a title bar with the type of entity • a zone corresponding to a name • a zone corresponding to a comment • different tabs containing the specific characteristics of the entity

Example:

Properties sheet of geometric parameter PCENT

Entities identified by a number

The properties sheet of entities identified by a number contains the following information: • a title bar that contains the entity type and the entity number • different tabs containing the specific characteristics of the entity

Example:

Properties sheet of line n°5





4.2. Selection of entities

Introduction The most part of actions for handling the entities require the selection of

entities. Different modes of selection and different situations are treated in this section.


• General presentation of selection modes • Selection of entities (graphic mode) • Selection by relation (principle) • Other selection modes • Multiple selections (mono-selection and multi-selection)

Reading advice The operations of handling and selection of entities are interdependent. The

user will find information on the selection of entities in the section: “Handling the entities”.



4.2.1. General presentation of selection modes

Context The most actions of manipulation of entities require the selection of entities:

• to modify the coordinates of a point, you should select the corresponding point,

• to add a line (segment), you should define extremity points and then select starting point and ending point.

Selection circumstances

Selection of entities could be done in different circumstances. Examples are presented in the table below.

Direct selection Example: Line selection (with the mouse) in the graphic area

Selection from a selection box Example: Lines selection by number in a selection box

Selection from a properties sheet Example: Points selection by number in the properties sheet of the line n°5




Selection modes: overview

Selection of entities could be done with different selection modes: • graphic selection:

the user selects entities with the mouse in the FLUX window (graphic area, data tree or selection tree)

• selection by name or by number: the user enters the number or choose the name of the entities

• selection with an other mode: the user chooses an other selection mode in the menu accessible from the icon

• multiple selection: the user selects a set of entities (or group of entities) using different selection mode

The selection modes

The different selection modes are gathered in the table below.

Main selection modes (1)

Graphic Selection with the mouse in the graphic area or in the trees Number Selection by number (graphic object) Name Selection by name (abstract entity)

Other selection modes (2)

Select all Selection of all the entities of a specific type Unselect all Unselection of all previous selected entities

Select last instance Selection of the last selected entity Select last group Selection of the last group of selected entity

Select by coordinate Selection of the entity the closest to the coordinates entered.

Relation Selection by the intermediary of an other entity

Tools for selection management

Tools for selection management (allowing multiple selection) are presented in the table below.

Tools for selection management (3) Remove to remove entities in the list

Add to add entities in the list Intersection to realize intersection between two groups of entities



4.2.2. Selection of entities (graphic mode)

Graphic mode The selection in graphic mode is done directly with the mouse in the FLUX

window. It is the quickest and more convenient mode.

Entity type and selection area

The user selects entities in the graphic area, the data tree or the selection tree.

The different possibilities depending on entity type (graphic object or abstract entity) are presented in the table below.

Type of entity Data tree

Selection tree

Graphic area

Graphic objects (yes) yes yes Abstract entities yes no no

For graphic objects: It is recommended the selection in the selection tree (instead of data tree). The selectable objects are then displayed in bright colors in the graphic area.

The selection of graphic objects needs the preliminary choosing of the type of selected object (example: points or lines, or surface elements, …).

Choice of the type of the object to select

This choice is managed in the Filter graphic / Selection menu

The selectable entity type is marked with a ν in the list.

It’s possible to inactivate the selection (nothing selectable) with the use of None option

Selection options for display

Different options concerning the brightness of the selected objects are proposed for the display in the graphic zone. • display of selected objects with large lines • display of selected objects with opposite color • attenuation of other objects • display of labels of selected objects

The selection options are available: in the Tools / Options / Selection options menu




Select in the graphic area

To select a graphic object: • in the Graphic filter menu, point

Select and click on the type of desired entity (or corresponding icon)

• point directly on the entity

Select in a tree To select an entity in one of the trees:

• choose the tab corresponding to the tree (Data or Selection)

• point directly on the entity



4.2.3. Selection by relation (principle)

Principle All the entities are connected one to another by relations.

For example: • a volume is connected to the bordering faces • a face is connected to the bordering lines • a line is connected to the ending points, …

Thus, it is possible to select all the lines bordering a face by selecting this face, or all faces bordering a volume by selecting this volume.

The set of existing relations is rich and the user can easily decide what to select: • faces belonging to the same surface • lines with the same visibility, or with the same color, ... • points carrying the same mesh point • points delimited a face…

Operation mode

The selection by relation uses the relations existing between different entities. It is carried out in three steps (table below).

Step Description Example

1 The user specifies the entity type to be selected

Selection of lines

2 Then, he indicates by means of which entity he want to carry out the selection

Link to volumes

3 And finally, he selects the entities of interest

Selection of volumes



4.2.4. Other selection modes

Other modes and situations

The other selection modes allow us advanced selections (selection by relation, by group of by the same type of entities, …). These other modes are available in the following situations: • selection starting from a selection box • selection starting from a properties sheet

To reach the other selection modes, it is necessary to pass by the Data menu or by the data tree (and the contextual menu).

The access to the other selection modes is done by clicking on the button

Other selection modes

An overview of the Other selection modes is presented in the table below.

Other selection modes (2)

Select all Selection of all the entities of a specific type Unselect all Unselection of all previous selected entities

Select last instance Selection of the last selected entity Select last group Selection of the last group of selected entity

Select by coordinate Selection of the closest entity to the coordinates entered

Relation Selection by the means of an other entity

The other commands of the menu presented above (Add, Remove, Intersection) are described in the paragraph 4.2.5 “Multiple selections (mono-selection and multi-selection)”.

Operation mode

To select an entity or an entity group by using the other selection modes, the user should click on the button and choose the desired selection mode from the proposed list.




Select by relation

To select an entities group by relation:

Step Action

1 In the first box (selection box or properties sheet) : click on

2 Click on Relation and click on the desired relation Selection by… 3 In the second box (box of selection) :

• select the desired entities • click on OK to validate the information

4 In the first box: click on OK to validate the information



4.2.5. Multiple selections (mono-selection and multi-selection)

Multiple selections: principle

It is possible to distinguish two operation levels • level 1 :

selection of an entity or a group of entities (one at the same time) • level 2 :

selection and management of an assembly of entities, or an assembly of groups of entities (multiple selection)

Selection management tools

The selections management tools allow us the selection and the management of an assembly of entities or groups of entities.

The selections management tools are presented in the table below.

Selections management tools (3) Remove to remove entities from the list

Add to add entities in the list Intersection to carry out the intersection of two groups of

selection

Operation mode

To carry out a multiple selection (assembly of entities or group of entities), the user proceeds in the following way :

Step Description

1 The user carries out a 1st selection (mode of his choice) 2 Then, he clicks on the button to access the selections

management tools 3 He clicks on the desired selections management tool

Add, Remove or Intersection, and 4 He carries out a 2nd selection (mode chosen from proposed list) 5 Then, the user can:

• close his assembly, by clicking on OK • modify his assembly, by beginning again with step 2





4.3. Data handling

Introduction The building of a FLUX project consists in the handling of the entities.

The basic operations for handling the entities are the following: Add, Edit, Modify or Delete.


• Creation of entities • Editing / Modifying the entities • Deletion of entities

Reading advice The operations for handling and selection of entities are interdependent. The

user will find basic information on the selection of entities and detailed information on the various selection modes in the section: "Selection of entities".



4.3.1. Creation of entities

Principle To create a new entity:

• the user should open a new sheet (of desired entity type) • and enter the information necessary to define this entity.

Name by default

When creating entities identified by a name, the names are proposed by default.

The proposed name contains an abbreviation followed by a number.

Create an entity

To create a new entity:

Step Action 1 Open a new sheet of desired entity type:

In the Data menu, In the Data tree, • click on Add • select the Entity type • select the Entity type

from the proposed list • click on Add in the

contextual menu (or double click on the Entity type)

2 Fill in the Name of entity zone in the properties sheet (if the entity is identified by a name): • Keep or modify the name proposed by default • Add a comment, eventually

3 Fill the other zones: • Keep or modify the options by default • Enter the specific characteristics of entity

3 Click on the Ok button to validate the information 4 If you want:

• to create a new entity of the same type: return to step 2

• to quit the sequence: click on Cancel

Message in the Console window

When creating an entity, FLUX emits a message in the Console window to inform the user about the evolution of operation. PARAMETER_GEOM(EXPRESSION=SCAL_I(C80='33'), NAME='PARAMETER_GEOM1 ') PARAMETER_GEOM(2) created



4.3.2. Editing / Modifying the entities

Edition and modification

The user can edit an entity to check or to modify its characteristics. In both cases, he should open the properties sheet of an entity, then close it again after checking (Edit) or modification (Modify).

These two operations are grouped in the same menu: Edit/Modify.

Principle To edit an entity:

• the user should select the entity to edit or to modify: - either directly, or (1) - from a selection box (2) and open the properties sheet of this entity,

• then modify the entity: (3) enter the new information concerning characteristics, …

Modify an entity (1)

To edit or modify an entity (directly):

Step Action 1 Select with the mouse (graphic mode) the entity to modify

(Keep pressed the Ctrl key for a multiple selection) 2 Open the properties sheet:

• double click on the entity, or • click on Edit/Modify in the contextual menu





To edit or modify an entity from a selection box:

Step Action

1 In the Data menu In the Data tree • point Edit/Modify • select the Entity type • select the Entity type in

the list • click on Edit/Modify in the

contextual menu

2 In the selection box:

Abstract entity Graphic object

Choose names Enter numbers

Click on Ok to validate information, close the selection box and open the properties sheet.


To modify the entity (enter the new information concerning characteristics, …)

Step Action

3 In the properties sheet: • modify the concerned area

4 Then, choose one the following action: • To validate the information without closing the sheet: click on

Apply, then resume from step 3 • To validate the information and close the sheet : click on Ok • To close the sheet without validating the information: click on

Cancel

Message in the Console zone

When an entity is created, FLUX emits a message in the Console zone to inform the user about the evolution of operation. TRANSF['TRZ_10'].TRANS_VEC=TRXYZ_I (COO_SYS=COORD_SYS['XYZ1 : Systeme de coordonnees cartesien Cartesian coordinate system.'], DELTA=[SCAL_I(C80='0'), SCAL_I(C80='0'), SCAL_I(C80='2')]) TRANSF(1) modified



4.3.3. Deletion of entities

Deletion and deletion in force

The user can delete an entity if this one is independent. However, an entity is very often connected to other entities and the deletion of an entity involves the destruction of all the entities that depend on this one.

There are two deletion modes: • "simple" deletion:

The user can destroy an entity if this one is independent (i.e. not connected to other entities).

• "in force" deletion: The user can destroy any entity, destroying in the same time all the entities connected to it. These two modes are briefly described in the table below.

Mode Destroyable entity What is destroyed simple independent selected entity in force any selected entity + entities connected to it

Principle To delete (or delete in force) an entity:

• the user should select the entity to delete: - either directly, or (1) - from a selection box (2)

• then, confirm the entity (or set of entities) deletion (3) In forced mode, the user is informed before the deletion of the identity of the dependent entities which will be destroyed by the operation of deletion (list of the names and numbers)

Delete an entity (1)

To delete an entity (directly):

Step Action 1 Select with the mouse (graphic mode) the entity to modify

(Keep pressed the Ctrl key for a multiple selection) 2 Click on Delete (Delete Force) in the contextual menu





To delete an entity (from a selection box):

Step Action

1 In the Data menu In the Data tree • point Delete • select the Entity type

(Delete Force) • click on Delete • select the Entity type in

the list (Delete Force) in the contextual menu

2 In the selection box

Abstract entity Graphic object

Choose names Enter numbers

Click on Ok to validate information


To delete an entity:

Step Action 3 In the confirmation box:

• Click on Yes, if you want to delete the entity or the set of entities • Otherwise, click on No

Message in the Console zone

Result: • When an entity or a set of entities is deleted, FLUX emits a message in the

Console zone to inform the user about the evolution of operation Line[11].delete() TRANSF['TRZ_10'].delete()

• When it is not possible to delete an entity, FLUX emits a message: Line[1].delete() *** OCDNUM: Occurrence RB.F3D.LIGNE(1) locked *** *** OCDNUM: Deletion of occurrences aborted *** *** deleteProjectInstance: failed ***



4.4. Visualization of entities

Introduction This section deals with the graphic representation of the modeled device.

When referring to the graphic representation of a device, we are interested: • on one hand, in the type of displayed view: side view, top view, bottom

view, global view, … in its position and dimensions in the graphic display zone

• on the other hand, in the different entities and their appearance: points and their visibility, lines and their color, faces, surface elements….

The first aspect of the graphic representation (called viewpoint) is treated in chapter “Environment and graphic representation” The second aspect of the graphic representation (called visualization of entities) is treated in this chapter.


• Display and appearance of entities • Visualization of entities: display of entities • Visualization of entities: graphic appearance



4.4.1. Display and appearance of entities

Introduction The graphic representation of different objects is not the same during the

different steps of building the numerical model of the device.

From a step to another, we are interested in: • representation of points and lines during the geometry building • representation of nodes and surface elements during the mesh building, ….

Examples

Possibilities to modify the visualization

To control the graphic representation, FLUX provides default settings, but the user has also the possibility to modify this representation.

For this, the following commands are available: • the Display command (Graphic filters menu), which manages the list of

types of entities to display, • the general command of data manipulation, Modify, which allows the

modification of appearance (characteristics of visibility, color, aspect, …)



4.4.2. Visualization of entities: display of entities

Subject How to make appear the desired representation of the device in the graphic

window, in terms of entities displayed on the screen: all the points, or the points and the lines, or only the faces, …

Displaying rules

The entities displayed in the graphic window are those, whose types are presented in the display list.

This list is “co-managed” by the program and by the user: • The management of the list is ensured by the program following the

propagation and priority rules • The user can use the Display command of the Graphic filters menu, or the

corresponding icons.

Display list The display list contains the different types of entities represented in the

graphic zone.

Graphic filters/Display Menu

Display Toolbar

Modify the list To modify the display list:

• Click on Display in the Graphic filters menu and click on the desired type of entity,

or • Click on the corresponding icon in the Display toolbar

Result Normally, the modifications are directly visible on the screen.

If it is not the desired result, you may modify the graphic representation of entities (appearance of entities) and, especially the visibility characteristics.



4.4.3. Visualization of entities: graphic appearance

Subject How to make appear the desired representation of the device in the graphic

window, in terms of graphic appearance of entities: visibility, color, …

Appearance The possible appearances are presented in the table below:

Appearance Characteristics color visible or invisible visibility white, cyan, yellow, magenta, black, red, turquoise and green.

Appearance in the properties sheet

The entities in the graphic window are displayed according to their appearance characteristics (visibility, color, …) For each entity, the characteristics are saved in the Appearance tab of the properties sheet.

Modify the appearance

To modify the appearance of an entity:

Step Action

1 Select the entity and open the properties sheet 2 Choose the Appearance tab:

• Choose a color from the proposed list • Choose a visibility

3 Close the sheet


FLUX® 9.10 Command file, Python language

5. Command file, Python language

Introduction The Python language is a programming language that can be used to control

Preflux (automation of certain tasks by using command files).

This chapter deals with the implementation of command files in Preflux and provides basic information about the Python language.


• To begin • FLUX and Python language • Examples of command files

Warning This chapter is not a course of Python language. It is intended only for stirring

your interest by two simple examples and for opening new perspectives to the user.


Command file, Python language FLUX® 9.10



5.1. To begin

Introduction This section refers to the know-how you must posses before being able to

treat various examples.


• What can we do with the command files? • How does it work?



5.1.1. What can we do with the command files?

Introduction Instead of manually executing series of repetitive actions in FLUX, you can

save time by building and executing a command file that performs the task in your place (equivalent of a WORD or EXCEL macro).

Command file: definition

A command file is a series of FLUX commands and instructions written in the Python language intended to execute automatically a task.

Interest A command file is useful for:

• accelerating the most frequent operations • associating several commands • performing a complex series of tasks automatically

Example 1 In the mesh building phase, you must create the «mesh parameters» which

you will use to adjust the mesh (Mesh Point and Mesh Line).

By default, there are three Mesh Point: SMALL, LARGE and MEDIUM, but there is no a predefined Mesh Line.

By means of a command file, you can create a series of Mesh Line (A1, …, A10) that will be available for meshing your study domain.

Example 2 When you perform a multi-parametric study with FLUX3D, first you evaluate

the number of cases to be solved. If the number of parameters is significant, the number of computations (L*N*M*…) and, consequently, the computation time can be significant.

As part of an experimental test table, you may be interested only in a certain number of cases, respectively in a specific combination of different parameters).

Through a command file you can prepare and solve only the desired cases.



5.1.2. How does it work?

Introduction The automation of tasks through a command file, involves:

• the creation of a command file • the execution of this command file

Creation of a command file

There are two modes of creating a command file: • mode 1: by writing the file based on a saved sequence • mode 2: by directly writing the file

Mode 1 The different steps of this easiest mode of command file creation are

described in the following table.

Step Description Context 1 Saving of a FLUX command sequence to a spy file Preflux 2 Creation of a command file:

• based on the previous spy file • using the instructions of Python language

Text editor

Mode 2 This type of command file creation is more complex and requires a good

understanding of the FLUX data base structure.

Save a spy file To save a command sequence in a spy file:

• In the Project menu, click on Spy file and click on Open • In the Save as box, enter a file name

At this moment, all the FLUX commands are saved in the spy file.

Execute a command file

To execute a command file proceed as follows: • In the Project menu, click on Command file and click on Execute • In the Open box, enter the file name

At this moment, all the FLUX commands (and Python instructions), saved in the spy file, are executed.





5.2. FLUX and Python language

Python: what is this?

«Python is a portable, dynamic, extensible, free language which allows a modular and object oriented approach of the programming. Python has been developed since 1989 by Guido van Rossum and several voluntary contributors», in «Learn to program with Python» by Gérard Swinnen.

All the information about this language is accessible on the Python site: http://www.python.org


• Python language syntax: general principles • Python in the FLUX environment • FLUX commands and Python language

Warning The user will find only the necessary information to understand the two

simple examples treated in the following section.


http://www.python.org/


5.2.1. Python language syntax: general principles

File Python files have the extension: .py

General rules General rules:

• A line should contain only one instruction • All the comments begin with the character # and continue until the end of

the line • Names should begin with a letter or a _, and may contain letters, numbers

and the character _ • Blocks are marked by indentation (in standard version, 4 spaces. The

tabulations are prohibited)

Variables and types

Declaration, assignment of variables: • It is not necessary to declare the variables. A variable is created at its first

assignment by means of = operator • The variables have no fixed type. The type of a variable is the type of the

value that is assigned to it. The types of standard data are: • numerical types : integer, floating, complex 312 3.13e10 0.1256 3.2+0.5j

• character strings : between apostrophes or quotation mark 'hello' , "followed by information"

• sequences : character string, n-uplets, lists (1,2,3) 4,5 (1,)

Tests The key word if serve to test a value

if test 1 : #bloc test 1 true elseif test 2 : #bloc test 2 true else : #bloc default

Loops There are two types of loop:

• for loop, to reiterate on the values of a sequence

for variable in sequence : #loop block

• while loop, to reiterate as long as a condition is satisfied

while test : #loop block




Functions A new function is defined using the key word def.

Example :

The function add defined below, ads 2 numbers or join two character strings. def add (a,b) : return a+b



5.2.2. Python in the FLUX environment

Introduction Python language can be used in two different modes in the FLUX

environment: • in script mode, in the command files • in interactive mode, directly in the command bar (Python bar)

Command bar (Python)

The command bar (or Python bar) is the display zone situated between the graphic and console display zones.

It allows the use of Python language in interactive mode.

Principle of use You can enter the Python instructions directly in the command bar:

• in the zone FLUX-Python > The «answer» is then displayed in the console bar, just below.

Example You can use Python as a calculator. An example is presented in the table

below.

In the bar of… command enter the expression Flux-Python >8+3*2 console read the result 8+3*2

14

Attention The variables, Python functions, … are preserved as long as the Preflux

module is opened.



5.2.3. FLUX commands and Python language

Introduction All FLUX commands have their translation in Python language.

To learn the syntax of FLUX commands in Python language, you can use one of the following methods: • read the syntax from an existing spy file (the easiest method) • use the instruction .help.

Instruction .help

You can obtain information about the structure of the FLUX data by means of the instruction .help.

The syntax is as follows: EntityName.help ()

Example To obtain information about the structure of the Geometric parameter

entity:

Enter the following instruction in the command bar: Flux-Python > ParameterGeom.help()

Read the following information in the console bar: ParameterGeom (Entity for parametrizing a geometry): Type Entity (read write) Fields : -ParameterGeom[id name].expression (Parameter expression) : [1...1] of SCAL_I (read write) -ParameterGeom[id name].name (Parameter name) : [1...1] of C80 (read write) -ParameterGeom[id name].value (Parameter value) : [1...1] of R08 (read write)

FLUX entities The different FLUX entities are listed in the table below

Domain type DomainType.help() Infinite box InfiniteBox.help() Periodicity Periodicity.help() Symmetry Symmetry.help() Geometric parameter ParameterGeom.help() Coordinate system CoordSys.help() Transformation Transf.help() Point Point.help() Line Line.help() Face Face.help() Point region RegionPoint.help() Line region RegionLine.help() Surface region RegionFace.help() Mesh Point MeshPoint.help() Mesh Line MeshLine.help() Mesh generator MeshGenerator.help()





5.3. Examples of command files

Introduction This section describes the implementation of command files in case of two

simple examples (results already presented in the section «What can we do with the command files ? »).


• Example 1: automatic creation of a series of line mesh • Example 2: automatic preparation of a series of FLUX projects ready to be

solved

Reading advice The two examples can be described either with Preflux 2D or with Preflux 3D.



5.3.1. Example 1: automatic creation of a series of line mesh

Objective The objective is to write a command file for the automatic creation of a series

of Mesh Line.

Example: The file allows the creation of ten Mesh Line (A1, …, A10) of arithmetic type with (1, … , 10) elements.

This command file can be used for different FLUX projects.

Operation mode

The operation mode includes the following actions : • Save in a spy file the sequence of creation of a Mesh Line (step 1) • Write the command file, based on the previous file, through the Python

language (step 2) • Execute this file to test it (step 3)

Step 1 Save in a spy file the sequence of creation of a Mesh Line

Step Action 1 In the Project menu:

click on Spy file and click on Open

In the Save as box: enter the file name: CreerDiscLin.py

2 In the data tree: double click on Mesh Line

3 In the properties sheet: • fill in different zones:

• Click on Ok

In the new properties sheet: Click on Cancel

4 In the Project menu click on Spy file and click on Close




Final result step 1

The spy file (CreerDiscLin.py) containing the saved sequence appears in the following way:

Spy file: interpretation

Interpretation of the spy file:

Element Function #! Preflu3D 8.10 indication about the program this file was

saved by MeshLineArithmetic (name=’A1’, color=Color[‘White’], number=1)

creation of a Mesh Line with the following characteristics : (name = A1 / color = white / number = 1) (FLUX command)

Complements of Python syntax: • the symbol "#!" is used for writing executable scripts

Step 2 Write the command file based on the previous spy file:

Step Action 1 Write directly, in the spy file (CreerDiscLin.py), the necessary

instructions (in Python language) for the creation of a series of Mesh Line.

The instructions to be written are explained below: for i in range(9) : nom = 'A' + (i+1).toString() MeshLineArithmetic(name=nom, color=Color[‘White’], number=I+1)

2 Save the file




Command file: interpretation

Interpretation of the command file:

Element Function #! Preflu3D 8.10 indication about the program this file can be used

with (compulsory line) for i in range(9) : realization of a for loop to reiterate on the values

of the sequence (0, …, 9) name = 'A' + (i+1).toString()

creation of a variable name which takes the successive values A i+1 (A1, A2, …, A10)

MeshLineArithmetic (name=name, color=Color['White'], number=i+1)

creation of a Mesh Line with the following characteristics: (Ai+1 / space/ i+1) (FLUX command)

Complements of the Python syntax: • the function range generates a list of integers • the instruction toString converts the numerical type in character string type

Step 3 Execute the command file:

• In the Project menu, click on Command file and click on Execute • In the Open box, enter the file name CreerDiscLin.py

Final result step 3

After executing the command file, the user will have 10 line mesh entities available in the current FLUX project: A1 = 1, A2 = 2, … , A10 = 10



5.3.2. Example 2: automatic preparation of a series of FLUX projects ready to be solved

Objective The objective is to study 3 specific configurations of a parameterized

rectangle defined by 6 parameters: X1, Y1, X2, Y2, X3, Y3.

Operation mode

The operation mode supposes the following actions: • Prepare a FLUX project containing the base geometry (step 1) • Save in a spy file the sequence of the geometry modification (with mesh

rebuilding) (step 2) • Write the command file based on the previous file through the Python

language (step 3) • Execute this file to test it (step 4)

Step 1 To build the base geometry on which the modifications are done, you can

either execute the command file given in the annex, or follow the procedure:

Step Action 1 Open a new FLUX project 2 In the Geometry context:

• create the following 6 parameters: X1 = 20 / Y1 = 0, X2 = 0 / Y2 = 10, X3 = 20 / Y3 = 10 ;

• create the following 4 points: (0, 0) ; (X1, Y1) ; (X2, Y2) ; (X3, Y3) ;

• create 4 lines to close a rectangle with these 4 points ; • build the faces

3 In the Mesh context: • modify the value of the MEDIUM Mesh Line (value : 1 mm) • assign the MEDIUM Mesh Line to the 4 points • mesh the faces

4 Save the project under the name Base.FLU

Final result step 1

The project Base.FLU contains • 4 parameters, • 4 points (3 are

parameterized) • 4 lines (segments) • 1 meshed face

(X3 = 20, Y3 = 10)

(X1 = 20, Y1 = 0)

(X2 = 0, Y2 = 10)

(0, 0)




Step 2 Save in a spy file the modification sequence:

Step Action 1 Open a spy file (ModifParam.py) 2 Carry out the modification actions:

• delete the mesh (to allow the geometrical modification) • modify the value of a geometrical parameter • mesh the faces • save the project under another name

3 Close the spy file

Final result step 2

The spy file (ModifParam.py), containing the saved sequence, has the following form:

Step 3 Create the command file based on the previous spy file:

Step Action 1 Write a function (in Python language) which allows the

automatic creation of a FLUX project (corresponding to a set of parameters) starting from a base project Base.FLU.

The written function is explained below : def modify(VX1, VY1, VX2, VY2, VX3, VY3, case) : deleteMesh() ParameterGeom['X1'].expression=VX1.toString() ParameterGeom['Y1'].expression=VY1.toString() ParameterGeom['X2'].expression=VX2.toString() ParameterGeom['Y2'].expression=VY2.toString() ParameterGeom['X3'].expression=VX3.toString() ParameterGeom['Y3'].expression=VY3.toString() meshFaces() saveProjectAs(case)

2 Write the calls of the previous function to create the 3 desired cases modify(10,0,0,10,20,10,"Case1") modify(10,0,10,10,20,10,"Case2") modify(10,0,0,10,15,5,"Case3")

3 Save the command file




Command file: interpretation

The modify function defined in the command file allows the creation of a new FLUX project named case, in which the geometrical parameters X1, Y1, X2, Y2, X3, Y3 take the following values VX1, VY1, VX2, VY2, VX3, VY3

Element Function

#! Preflu2D 8.10 indication about the program this file can be used with (compulsory)

def modify(VX1, VY1, VX2, VY2, VX3, VY3, case) :

definition of the modify function having as input variables : 6 parameters and 1 name

deleteMesh() deletion of the mesh ParameterGeom['X1'].expression=VX1.toString()

modification of geometric parameter X1 (taking the value VX1)

meshFaces() mesh the faces saveProjectAs(case) save the project (under the name case) modify(10,0,0,10,20,10, "Case1")

call of the function to build the first case

… call of the function to build the next two cases

It is necessary to convert the parameter value by a FLUX command from numerical type to character string type.

Step 4 Execute the command file.

Final result step 4

After executing the command file, the user has in his working directory, 4 FLUX projects whose characteristics are given in the table below.

BASE.FLU CASE1.FLU CASE2.FLU CASE3.FLU

P2 P3

P1P0 P1: (20, 0) P1: (10, 0) P1: (10, 0) P1: (10, 0) P2: ( 0, 10) P2: ( 0, 10) P2: (10, 10) P2: ( 0, 10) P3: (20, 10) P3: (20, 10) P3: (20, 10) P3: (15, 5)




FLUX® 9.10 Geometry: principles

6. Geometry: principles

Introduction This chapter gives the necessary knowledge to describe the geometry: study

domain definition and symmetry or periodicity use, FLUX geometry building module, geometry building tools, …

This chapter also presents the general principles of geometry building and some considerations on the modeling strategy.


• Modeling strategies • Study domain • Characteristics of geometry building module • Tools of geometry building module • Geometry building: general steps


Geometry: principles FLUX® 9.10



6.1. Modeling strategies

Introduction This section presents some considerations on the modeling strategy.

It is about properly defining the study type to be carried out (2D plane, 2D with revolution symmetry, 3D) before choosing the 2D or 3D FLUX application.


• 2D plane study, 2D axisymmetric study, 3D study



6.1.1. 2D plane study, 2D axisymmetric study, 3D study

Preliminary consideration

Before starting the description of a device, it is necessary to answer the following questions: • What type of study is possible to carry out on this device ? • What application should be used: Preflu2d or Preflu3d ?

Different study types

It is possible to distinguish the following different study types.

Study type Device characteristics Geometric representation

2D plane device supposed infinitely long in one direction in a cross section plane

2D axi symmetric

device having a revolution symmetry around an axis

in a cross section plane that contain the revolution axis

3D unspecified complete

Note on the vocabulary used: We speak about an axisymmetric study in FLUX2D when the device has a revolution symmetry around an axis.

2D plane study: characteristics

It is possible to carry out a 2D plane study if the device is supposed infinitely long in one direction.

The geometric representation of the device is carried out in a cross section plane (normal to this direction).

The device depth is taken into account (at physical level) to compute the global quantities (force, energy, …)

Example

real object

y

x

z

2D plane geometry

y

x




2D plane study: working assumptions

Working assumptions : The device is supposed infinitely long along a direction (depth). The magnetic flux is concentrated on the cross section plane, there is no extremity effect (magnetic flux leakage) in the 3rd direction (depth). Possible interpretations of these working assumptions: • The air gap thickness is reduced with respect to the device depth. • The magnetic flux leakage in the 3rd direction is neglected.

Example : 2D plane study or 3D study?

Two devices are represented in the figure below. These two devices are built on the same support (from the geometric point of view), but they do not function in the same way (from physical point of view).

Device consisting of: • two magnets in opposition • two magnetic cores (2 yokes)

Device consisting of: • two inductors • a magnetic circuit

Long device, but important 3D effect (leakage at extremities)

Long device and magnetic flux concentrated in the magnetic circuit

Discussion on the 2D/3D choice: • From geometric point of view:

These two devices can be described on cross section planes. Thus, a 2D study can be considered in both situations.

• From physical point of view: - a 3D study is recommended in the 1st situation, because there is an

important magnetic flux leakage at the back and in the front of the device (due to the magnets in opposition).

- a 2D study is recommended in the 2nd situation, because the magnetic fluxes, created by the inductors, have the same orientation. Thus, the magnetic flux is strongly confined in the magnetic circuit, and therefore in the cross section plane.

3D study In this type of study any geometry can be represented, but within the software

possibilities limits.




2D axisymmetric study: characteristics

It is possible to carry out a 2D axisymmetric study if the device has a revolution symmetry around one of the axis.

The geometric representation of the device is carried out on a cross section plane.

Pay attention, the revolution axis of the geometry should be obligatorily vertical and should pass through the origin of the coordinate system. Although we speak about a 2D study (plane geometric representation), we deal in fact with a 3D study. The device is entirely modeled, the global results being provided for the whole volume of the device.

Example

Z

R

2D axisymmetric geometry

y

x

z

real object

Choice of the application

The choice of the application (2D or 3D) is carried out at supervisor level (FLUX2D or FLUX3D tabs).



6.2. Study domain

Introduction This section refers to the definition of the study domain, i.e.:

• the definition of the study domain limits (device model) • the possibilities of reduction the study domain with respect to the real

device by taking into account the repetitive patterns like periodicities and/or symmetry planes of the studied device.


• Study domain limits, generalities • Truncation method • The infinite box transformation • Reduction of the study domain: symmetries and periodicities • Periodicity property and periodicity conditions on the boundaries • Symmetry and symmetry conditions on the boundaries



6.2.1. Study domain limits, generalities

Electromagnetic phenomena

In the study of electromagnetic phenomena it is necessary to model both the device and the surrounding air. In fact, the quantities studied in electromagnetics (electric fields, magnetic fields), are not considered null in air or in a vacuum, contrary to other physics disciplines, mechanics, for example, where air is not taken into account.

Finite element method

The finite element method is based on the subdivision of the entire study domain in a finite number of sub domains of finite size. The physical problem is governed by a differential equation with partial derivatives that should be satisfied on all the points of a domain. To ensure the uniqueness of the solution, boundary conditions on the outer edges must be imposed. Thus, to solve a problem with the finite element method, it is necessary to: • set limits on the device model, i.e. to define the limits or boundaries of the

domain, • impose boundary conditions on the edges, i.e., to define the values of the

state variable (potential, temperature) on the boundaries of the domain.

Apparent contradiction

The finite element method requires limits on the problem region, while the electromagnetic phenomena are unlimited.

In other words, open domains cannot be modeled by the finite element method, because it is impossible to subdivide an infinite domain into a finite number of finite sub-domains.

Study domain limits: different methods

To offset this contradiction, different methods can be used.

The first method (the truncation method) consists of closing the study domain with an outer boundary sufficiently far away from the device so as not to interfere with the results.

The second method consists of using a transformation that converts the open domain into a closed domain.

These two methods are described in the following paragraphs.




Study domain limits: truncation method

The truncation method consists of closing the study domain with an outer boundary sufficiently far away from the device so as not to interfere with the results.

The device is placed inside an air–filled box, and infinity is approximated by a closed and remote truncation boundary. The size of the air-filled box is adjusted so that the effects of the truncation boundary approximation can be neglected.

The user must determine the quantity of air to model around the device, i.e., he or she must evaluate the distance at which the computed fields become negligible.

Truncation method: disadvantages

The truncation method has certain disadvantages: • relatively high cost in terms of numbers of unknowns • negligible field values near the truncation boundary

Modeling infinity: using a transformation

To compensate for these disadvantages, a second method consists of using a transformation that converts the open domain into a closed domain.

The basic idea is to transform the open domain into a closed domain because the open domain cannot be meshed.

Use of a transformation, principle

The intial space is decomposed into two domains: • a closed interior domain, Eint • an open exterior domain, Eext

The initial space, with open borders, is transformed into a final space with closed borders, in the following way: • the interior domain (Eint) is not modified • the exterior domain (Eext) is linked to a closed domain (Eext_image) through

a spatial transformation T.

Thus, the final space is composed of two domains: • a closed interior domain Eint • a closed exterior domain Eext_image

These two (closed) domains are meshed with classical finite elements.

Illustration

m ( x, y, z ) M ( X, Y, Z )

Eext Eext_image Eint

Eint

Transformation T




Use of a transformation, principle (continued)

To take into account the transformations in the equations, we suppose that : • the finite elements formulations are not modified (the state variable of the

initial domain and the state variable of the image domain are equal) • new types of finite elements (transformed finite elements) are able to model

infinity.

Illustration Representation of the exterior domain

m ( x, y, z )M ( X, Y, Z )

TransformationT

y

x

M (x, y)

Y

X

M (X, Y)

Transformed finite element Image element

Inversetransformation

T-1

Choice of the transformation

Theoretically several space transformations can be used. The transformation of the real space into an image space must be bijective. It must also have properties of continuity and derivability on and between the elements, etc.

In practice, the transformations used in the software take into account various efficiency criteria: quality of the solution obtained for a number of elements or unknowns, simplicity of implementation, and so on.



6.2.2. Truncation method

Introduction The truncation method consists of closing the study domain with an outer

boundary sufficiently far away from the device so as not to interfere with the most important results.

At what distance should be placed the border ?

To evaluate at what distance one should place the boundary, it is necessary to take into account the studied phenomena. Generally we can say that: • when the field is strongly confined within the structure (flux directed by

flux concentrators, Faraday cages, capacitor, etc.), a small quantity of air is sufficient. The boundary can be placed directly on the device outline or near it.

• when the field spreads strongly outside the structure (EMC, etc.), a large quantity of air is necessary. The difficulty consists in the estimation of this quantity.

Example Some rules for the positioning of the boundary for an open boundary

magnetic problem (device surrounded by air) are as follows: • for a 2D plane study or a 3D study:

the boundary should be placed at a distance ranging between 5 to 10 times the longest dimension of the device.

• for a 2D axi-symmetric study: in the direction normal to the revolution axis, the boundary should be placed at a distance ranging between 10 to 20 times the longest dimension of the device, the variable r*AZ decreasing slowly in this direction.

Boundary conditions

The user must impose boundary conditions on the external boundaries of the study domain.



6.2.3. The infinite box transformation

Infinite box: definition

In the terminology of the software, using a transformation to model an infinite domain is called the infinite box technique or method.

The exterior domain (infinite) is linked to an image domain (called the infinite box) through a space transformation.

The use of the infinite box implicitly assumes a null field at infinity.

Infinite box, FLUX3D

The transformation used in Preflux 3D, said to be in a parallelipipedic layer (not a skewed surface), is described by two superimposed parallelepipeds or cylinders. The faces of the exterior parallelepiped or cylinder are the image of the infinite, where the potential and field are equal to zero.

Interior domain

Exterior image domain,

i.e., infinite box Representation of the two domains by the software

Infinite box, FLUX2D

For Preflux 2D, the infinite box is described by two superimposed discs (crown shaped). The external circle is the image of the infinite.

Interior domain External image domain, i.e. infinite box

Representation of the two domains by the software




How to choose the dimensions ?

The dimensions of the infinite box are defined by the user. This requires a certain experience because there is no general rule.

We can, however, give some advice: • the distance between the device and the interior surface of the infinite box is

at least equal to the dimension of the device in this direction • the dimensions of the infinite box are related to the mesh. In FLUX3D, the

number of elements on the thickness of the box must be roughly equal (at least) to two (second-order elements) or to three (first-order elements).

The mesh and the size of the infinite box must take into account the phenomena studied, and the computations to be performed as follows: • if one is interested in computing a global or a local quantity inside the

device, it is unnecessary to refine the mesh of the infinite box; • if on the contrary, one is interested in computing the field created outside

the device, one should define a box of more significant size and refine the mesh inside.

It is recommended to parameterize the dimensions of the infinite box to adjust its size during the meshing.

Boundary conditions

FLUX automatically assigns boundary conditions on the infinite box.



6.2.4. Reduction of the study domain: symmetries and periodicities

The main ideas: decrease the study domain

In most cases, a preliminary analysis of the device highlights the presence of repetitive patterns (periodicities) or symmetry planes.

Under these conditions, it is possible to reduce the study domain as follows: • representation of a fraction of the device • assignment of appropriate boundary conditions on the model boundaries

that reflect the periodicity property or symmetry conditions.

Interest The consequences of a reduction of the device model are as follows:

• a simplification of the geometrical description • a reduction of the finite element problem size (and thus the file size).

The rationale for reducing the problem size is the reduction of the computation time. The computation time is roughly proportional to the square of the number of unknowns.

Example: If a problem comprises N unknowns, but after reduction of the model only N/2 unknowns, the global computation time will be reduced by a factor of 4.

Reduction of study domain and boundary conditions

It is possible to simplify the device model if it has geometrical and physical periodicities and/or symmetries at the same time.

In other words, it is possible to simplify the device model, when specific conditions applied on the state variable (potential) allow the representation of a fraction of the device.

The boundary conditions are physical concepts that are detailed in the “Physics” chapters of the FLUX2D and FLUX3D User’s Guides.

These concepts are briefly illustrated through a magnetic example (magneto-static, transient magnetic or magneto-harmonic application).




Example: presentation

The modeled device is a magnetic levitation device. It consists of a group of coils, a magnetic flux concentrator and a plate. Problem analysis: This device can be described as a group of repetitive linear patterns: a succession of coils in opposition. • from the geometrical point of view, the base pattern includes only one coil • from the physical point of view, the base pattern includes two coils in

opposition.

Example: different models

The authorized subdivisions of the model depend on the various types of boundary conditions set on the model boundaries. The various possible models are shown in the figures below. The boundary conditions set on the boundaries in these different configurations are explained in the following paragraphs.



6.2.5. Periodicity property and periodicity conditions on the boundaries

Periodicity When a device has repetitive patterns, it is possible to model a fraction of the

device (the basic pattern), and to impose appropriate periodicity conditions on the periodicity planes.

From a physical point of view, periodicity boundary conditions are set via the state variable (potential).

Periodicity condition

(or cyclic) Anti-periodicity condition

(or anti-cyclic)

Identical values of the variable on the

homologous nodes Opposite values of the variable on

the homologous nodes

Example Let’s reconsider the preceding example.

The boundary conditions to impose on boundaries 1 and 2 are periodicity conditions: • periodic type (or cyclic)

in the 1st case (study domain 1) • anti-periodic type (or anti-cyclic)

in the 2nd case (study domain 2 and 2')



6.2.6. Symmetry and symmetry conditions on the boundaries

Symmetry When a device has symmetry planes, it is possible to represent a fraction of

the device, and to set appropriate symmetry conditions on the symmetry planes.

From a physical point of view, the symmetry boundary conditions are set on the state variable (potential).

Symmetry condition Anti-symmetry condition

Example Let’s reconsider the preceding example.

The boundary conditions applied on the device boundaries are symmetry conditions (tangential field) on boundary 1 and anti-symmetry (normal field) on boundary 2.





6.3. Characteristics of geometry building module

Introduction This section deals with the operation of the geometry building module:

principle of construction algorithms, authorized shapes, difficulties that may occur during the construction of geometry, ...


• Presentation of the geometry building module • Lines and faces: authorized shapes • Lines and faces: superpositions and intersections • Limits of the geometry building module • Another functionality: nature of points, lines and faces



6.3.1. Presentation of the geometry building module

Introduction The geometry building module of FLUX is of boundary type, which means

that a volume is described by the bordering faces and a face is described by the bordering lines and a line is described by points.

Outline of the different steps

The geometry is created in ascending way: first the points, then the lines, and finally the faces and the volumes.

The table below gives a first outline of the description mode of the device geometry.

Step Description

1 Creation of points Manually by the user 2 Creation of lines Manually by the user 3 Identification/construction

of faces Automatically by the software

4 Identification/construction of volumes Automatically by the software

Creation of points and lines

The points and lines are defined manually (input of point coordinates, selection of the ends of the lines, …).

Construction of faces and volumes (new algorithms)

The faces and the volumes are automatically identified and created (algorithms of automatic construction).

Principle of automatic construction of faces: • FLUX computes all the existing surfaces and it determines to which

surfaces belong the points and the lines (A surface contains faces but it is not limited and it is defined by three points linked by two lines).

• The automatic creation of faces is then realized with the aid of a technique of identification of closed outlines.

The principle of the construction of volumes is similar, but more complex, due to the 3D effect.

Construction of faces and volumes (old algorithms)

In case of difficulties at automatic construction of faces and volumes, the old algorithms of automatic construction are available.

With the old algorithm, each surface is automatically meshed with very loose meshes. By grouping the topological surface elements, the software identifies the faces inside each surface.

The principle of the construction of volumes is similar, but more complex, due to the 3D effect.




Specificities of the geometry building module

To define the geometry description possibilities offered by the geometry building module, it is necessary to answer to the following questions: • What are the different authorized shapes of lines and faces ? • How are managed the intersections/superpositions of lines, of lines with

faces ? • What are the limits of the algorithms of identification and of automatic

construction of faces and volumes ?

These different items are treated in the following paragraphs.



6.3.2. Lines and faces: authorized shapes

Lines created by FLUX

FLUX enables to create the lines of following shapes: • segment • arc of circle • helical line

The helical line can be created only by using building tools for construction by extrusion.

Lines imported in FLUX

Within the geometry importation from IGES or STEP file and the mesh importation from NASTRAN, PATRAN or UNV file in the FLUX project, the lines of an unspecified shape are imported.

Faces created by FLUX

FLUX enables to create the faces of following shapes: • planar • cylindrical • conical • spherical • toroidal • helical

The complex faces such as the spherical, toroidal, helical ones can be created only by using building tools for construction by extrusion.

Faces imported in FLUX

Within the geometry importation from IGES or STEP file and the mesh importation from NASTRAN, PATRAN or UNV file in the FLUX project, the faces of an unspecified shape are imported.



6.3.3. Lines and faces: superpositions and intersections

Intersections and superpositions

The bordering property of the geometry building module entails the interdiction of the intersections of lines, of faces and of lines with faces.

The superpositions of line/face type, i.e. lines belonging to a face, or face/face type, i.e. faces belonging to a face, are authorized.

These different cases are presented below.

Intersections, superpositions of lines

The intersections and partial or total superpositions of the lines presented in the figure below are not authorized and in this case the construction of faces is not possible.

Lines belonging to faces

The lines belonging to faces are authorized. An example is presented in the next figure.

Lines L5 and L6 are internal lines of face F1. F1

F2 L4

L7

L6L10

L1

L3

L2

L8

L5 L9

Intersections of line/face type

The intersections of line/face type are not authorized, but they do not block the construction of faces and volumes.

Faces belonging to faces

Faces belonging to faces are authorized. An example is presented in the figure below.

FACE 1 described by 8 lines

FACE 2 described by 4 lines




Intersections of faces

The intersections of faces are not authorized and thus the construction of volumes is blocked. An example is presented in the figure below.

The faces of the parallelepiped intersect the circular face of the inner cylinder of the torus.

Thus, the faces and the volumes can not be built.

Intersections of faces: to avoid problems

To avoid the previous problem, it is possible to ignore some faces in the moment of volumes building (see paragraph 6.3.5 “Another functionality: nature of points, lines and faces”).



6.3.4. Limits of the geometry building module

Introduction The algorithms of automatic construction of faces and volumes are powerful,

but difficulties can however arise, being determined: • either by a «bad» geometrical description: problems of intersection or

superposition of entities, … • or by numerical problems, ….

Construction problems connected to intersection/ superposition of objects

Construction problems may occur in the presence of: • overlapping points, or lines of null length; • intersection or superposition of lines; • intersection of faces.

These different items are treated in the preceding paragraph.

Numerical problems of recognition of faces or volumes

Numerical problems of recognition of faces or volumes can also occur in the presence of faces characterized by too important numerical waves.

What is the problem ?

The algorithm of automatic construction of faces identifies in the first step all the existing surfaces, then, it determines to which surfaces belong the points and the lines. A surface is defined by four coefficients computed from the coordinates of three points. The test of association of points to surfaces is defined with an error criterion (epsilon tolerance criterion) and it may occur that the points and lines that the user consider in the same surface will not be considered in the same surface by the software. In this case, we speak about significant numerical waves.

This kind of situation may occur when the points are described by a "cascade" of parameters, of local coordinate systems and of transformations. When the point coordinates are evaluated in a global coordinate system, there is an accumulation of numerical errors and the tolerance is then exceeded.

In spite of a very particular care taken for solving these numerical problems, it may occur, in case of complex geometries, that the automatic construction of faces or volumes raises difficulties.



6.3.5. Another functionality: nature of points, lines and faces

Problems There is a certain number of situations where the user may want to modify the

consideration of the entities (points, lines, faces) during the automatic construction of the faces and/or volumes. Two examples are given hereafter to illustrate this type of situation.

The first example reconsider the problem of intersection between faces (blocking for building the volumes). This example has already been presented.

Example 1

In this example (figure to the right) the constitutive faces of the internal parallelepiped intersect the internal circular face of the torus. The volume of the bar inside the torus cannot be built.

To avoid this difficulty, it is necessary to ignore the two circular faces during the automatic construction of volumes.

Example 2 The second example consists in the numerical modeling of a ship (“La

Fayette” frigate of the French Marine represented in the figure below). The ship structure is only made up of bars which are represented and modeled via the lines (line regions). For this type of structure that is relatively complex, the use of the algorithm of faces and volumes construction is expensive, it often takes a long time and it generates many useless faces and volumes. To avoid this difficulty, we should place the lines within an air volume without building the group of faces and volumes that will not be used.




Solution: the nature attribute

To allow the user to modify the consideration of entities when building the faces and volumes, a specific feature (called nature) is attached to the points, lines and faces.

Attribute nature

The nature attribute allows us to set the following functions:

The entity is taken into account for: Nature the geometry the mesh Standard (STANDARD) yes Yes in air (IN_AIR) no Yes ignored (NO_EXIST) no No

Return to example 1

To ignore the annoying circular faces, the user should modify the nature of these faces (“ignored”) and restart the automatic building of volumes. These faces are then ignored at the geometry level (and also at the mesh level). Note: These faces are not destroyed. They still exist and are visible on the screen (in the visibility conditions that allow their visualization).

Return to example 2

To avoid the building of faces and volumes of the ship, the user should modify the nature of the points and lines of the ship (“in air”), then start the construction of faces and volumes. Thus, a single group of faces (boundaries of the study domain) and one volume (air volume that includes the group of lines and faces) will be built.

The points and the lines: • are not taken into account during the construction of faces and volumes • are taken into account during the mesh building and assignment of line

regions

The simplified geometry in a wire-mesh shape of the “La Fayette” frigate consists of about 3 300 points and 8 556 lines on which the (“in air”) nature has been imposed. These points and lines are placed within an air volume surrounded by the infinite box (24 faces and 7 volumes).





6.4. Tools of geometry building module

Introduction This section deals with the assisting tools for geometry building: parameter

setting, tools for rapid construction of particular patterns, ...


• Parameterization • Concepts of propagation and extrusion



6.4.1. Parameterization

Introduction The parameterization of the geometry is one of the strong points of the

geometry building module.

It is possible to parameterize: • dimensions of workpieces • relative displacements of pieces (variable air-gap, …).

Parameterization tools

A geometrical object can be parameterized: • on one hand, using the geometrical parameters, • on the other hand, using the local coordinate systems (coordinate

systems defined with respect to a reference coordinate system).

These concepts are presented in the example below.

Example The example refers to the study of a contactor, concerning the force acting

on the moving part for various values of the air-gap. The fixed part is defined in a local coordinate system REP1 of center (0, 0, 0), and the moving part in a local coordinate system REP2 of center (0, 0, AIR-GAP). AIR-GAP is a parameter whose value is equal to the air-gap thickness. To study various positions of the moving part, and thus various values of the air-gap, it is enough to modify the value of the corresponding parameter (AIR-GAP) and to treat the corresponding case.




Principle and limits

Each time that a geometrical entity is modified, all the entities depending on this geometrical entity are automatically reevaluated through the database tools.

Modifying a parameter or a coordinate system entails the modification of the points, then of the lines, and then of the faces and volumes that are attached to this parameter.

Important: the coherence of the topology (intersection, superposition, …) is not verified by the software. This verification is a user task.

In the previous example, a null value of the AIR-GAP parameter leads to a modification of the geometry topology that can not be realized due to superposed points and lines. This limit case can not be treated by parameterization.

Advice Defining local coordinate systems using a first coordinate system allows the

user to define a "father coordinate system", to which is attached a series of "children coordinate systems". By modifying the "father coordinate system" the user will modify the series of "children coordinate systems" attached to this first coordinate system and thus, the group of points, lines, …attached to it.

The user can also define a coordinate system in another coordinate system, and the latter defined in a third coordinate system, ... This description of intermediary coordinate systems “in cascade” can be useful, especially in case of multiple rotations. However, in this case, the risk of numerical problems for the algorithms of identification and construction of faces is more important.



6.4.2. Concepts of propagation and extrusion

Introduction To facilitate the geometrical description, various tools for automatic

construction are proposed. They allow the duplication of repetitive geometrical patterns, or the fast construction of structures presenting symmetries, ...

Using the FLUX vocabulary we speak about construction by propagation or extrusion. These concepts are clarified below.

Propagation, extrusion: definition

The basic idea is to automatically generate new objects, based on the objects already created (points, lines, faces) by using transformations; transformations are geometrical functions of translation, rotation, or affinity type.

At the vocabulary level, we speak about propagation when the created objects (images) are not connected to the basic objects (sources) and about extrusion when these objects are connected among them by connection elements. The connection elements can be of rectilinear or curvilinear type (straight segments or circle arcs).

These concepts are illustrated in the example below.

Example In the figure below, the basic face, a rectangle, is propagated/extruded using a

transformation of vectorial translation type. • The propagation automatically generates 2 new rectangles (4 points and 4

lines). • The rectilinear extrusion automatically generates 2 new rectangles (4 points

and 4 lines) as well as 8 connection elements (8 straight lines).



6.5. Geometry building: general steps

Introduction This section presents the general steps for building the device geometry


• Geometry building process • Logical commands sequence: simplified guide



6.5.1. Geometry building process

Outline An outline of the geometry building process is presented in the table below.

The different steps are detailed in the following blocks.

Step Description 1 Device analysis 2 Definition of the study domain 3 Preparation of the geometric construction tools 4 Ascending construction of the geometry 5 Regrouping in regions

Device analysis (1)

The first step of the geometry building process is the device analysis: • to define the study domain, and • to prepare the geometric description

The questions that could arise at this level, before starting the description itself, are grouped in the tables below (non exhaustive list).

Analysis to: Device features

define the study domain

• Does the device have geometric and/or physical symmetries or periodicities ?

• Can it be studied using the infinite box feature or should we limit the study domain in a different way?


prepare the geometric description

• Can the device be simplified without consequences on the study physics: approximation of complex shapes, removal of rounded corners, chamfered edges, holes, … ?

• Does it have moving parts, variable thickness, repetitive patterns, … ?

Analysis to: Is it necessary

prepare the mesh • to add points, lines, or faces in order to make easy the mesh building (skin depth, …) ?


prepare the physical description

• Does the device have specific shapes (such as thin bars, air gaps or magnetic armatures, …) that can be replaced by points, lines or faces (considered as point, line or surface regions) ?




Next steps (2, 3, 4, 5)

The other steps of the geometry building process are described in the table below.

The user Step of

… creates … builds … assigns …

Defining the study domain (2)

the symmetries the periodicities the infinite box

Preparing the geometric

building tools (3)

the geometric parameters

the local coordinate systems

the transformations

Ascending construction of

the geometry (4)

the points the lines

the faces the volumes

Regrouping in regions (5)

the point regions the line regions the face regions

the volume regions

the regions to points, lines,

faces, volumes respectively

Operations order

The different steps were presented in a «chronological» building order.

In practice, the geometry building process is not always linear and the user proceeds by successive steps. In this case, he makes “go and return” between different steps.



6.5.2. Logical commands sequence: simplified guide

Simplified guide

Logical commands sequence is presented in the synoptic hereafter. It is a simplified guide for geometric construction.

Definition of study

domain

Preparation of tools

Ascending building of

geometry

Rearrangement in regions

Create Periodicity

Create Periodicity

Create SymmetryCreate

SymmetryCreate

Infinite boxCreate

Infinite box

Create Geometricparameter

Create Geometricparameter

Create Coordinate

system

Create Coordinate

system

Create Transformation

Create Transformation

Create PointCreate Point

Create RegionsCreate Regions

Create LineCreate Line

Build Faces

Build Volumes

Assign Regions


FLUX® 9.10 Mesh: principles

7. Mesh: principles

Introduction This chapter gives the necessary knowledge for the mesh realization:

presentation of the different mesh generators available in FLUX, meshing strategies, …

It also presents the general operations of the mesh module (choice of mesh generator, mesh adjustment, …) and some considerations on specific meshes (thin regions, rotating air-gap, …)


• Mesh algorithms and field calculations: general points • Mesh strategies: mixed mesh or automatic mesh • Operation of the Mesh module: general steps • Mesh generators specificities and limitations • Description of specific meshes, examples


Mesh: principles FLUX® 9.10



7.1. Mesh algorithms and field calculations: general points

Introduction This section refers to the mesh algorithms (mesh generators) available in

FLUX.


• Mesh algorithms and field calculations: general points • Mesh and field calculations: different types of finite elements • A valid mesh: some rules to follow



7.1.1. Mesh algorithms: different mesh generators available in FLUX

Mesh: definition

The mesh is a subdivision of a domain into sub-domains called elements.

We discuss meshes or finite elements of the following types: • volume elements, for a volume domain • surface elements, for a surface domain • line elements, for a line domain.

Mesh generator: definition

A mesh generator is a tool to perform the subdivision into finite elements.

The algorithms for meshing (or mesh generators) used for subdivision are described below.

Delaunay mesh or automatic mesh

The Delaunay or automatic mesh algorithm is fairly general: it creates triangular elements on all the surfaces defined by their meshed outlines and tetrahedral elements on all the volumes defined by their meshed surface contours.

Example

Triangle Tetrahedron

“Topological” mesh or mapped mesh

This mesh generator allows the mesh of rectangular faces with rectangles (or quadrangular elements) and volumes such as parallelepiped with “bricks” (or hexahedron elements).

With the mapped mesh algorithm, the outline of a surface is divided into four lines, each one meshed so that two opposite lines have the same number of elements. The surface to be meshed is thus topologically equivalent to a rectangle. For the mapped mesh of a volume, the volume is topologically equivalent to a parallelepiped.

Exemple

Rectangle,

Quadrangle

“Brick”

Hexahedron




“Copy” mesh or linked mesh

This mesh generator allows you to impose the same mesh on faces linked by a geometrical transformation. This mesh generator can be used only for faces.

Example

Mesh by “movement” or by extrusion

This mesh generator generates a surface or volume mesh in layers on domains obtained by extrusion. This mesh is potentially anisotropic and the volume elements are prisms or hexahedrons, depending on the mesh of the base faces (triangles or rectangles).

With the extrusive mesh algorithm, a meshed line can be “moved” or shifted along a meshed path. (The movement must be simple, that is, translation or rotation.) Thus a mesh using quadrangles is generated. The same method is used to mesh volumes by moving or shifting a meshed surface.

Example rotation of a line

Example rotation of a face

“Prism” Pentahedron

“Brick” Hexahedron




The mesh on sub-domains or the mixed mesh

We divide the volume or surface domain to be meshed into sub-domains of simpler easy-to-mesh shapes using one of the following methods. The mesh on sub-domains or the mixed mesh is therefore a combination of the previous mesh generators.

The main difficulty with the mixed mesh is ensuring the coherence of the mesh on the interfaces between the sub-domains: the mesh on both sides of the sub-domain interfaces should be identical (we use the term mesh conformity). This conformity is not easy to obtain in 3D, when different mesh algorithms are used on neighboring sub-domains.

To ensure the coherence of the mesh on sub-domain interfaces, the 3D mixed mesh generator creates pyramidal volume elements that ensure the proper connection between triangular faces and rectangular faces.

Example



7.1.2. Mesh and field calculations: different types of finite elements

Finite element computation

The finite element based computation allows the approximation of state variables such as scalar or vector potentials, temperature, etc. and of derived quantities, such as magnetic field and induction, magnetic flux density, electric field, thermal flux density, etc.

The quality of the approximate solution depends on the mesh. Thus, the quality of the solution depends on: • the number and the dimensions of the finite elements • the interpolation functions in each element, which can be 1st, 2nd… order

polynomial functions, and on the continuity conditions imposed on the sub-domain boundaries.

A detailed presentation of the finite element based computation method goes beyond the scope of this document.

Nodal element, edge elements

In terms of the geometry, a volume element is characterized by its vertices, edges and faces.

facet

edge

vertex

In terms of the finite element computation, we can use: • nodal elements (computation on element nodes) • edge elements (computation on element edges).

Elements of 1st

and 2nd order Different types of finite elements are available to the user, and in FLUX terminology, these are called 1st order elements or 2nd order elements.

Specific information about these elements is presented in the following table.

Type of element

Position of nodes Interpolation function

1st order Vertices Linear (1st order polynomial) 2nd order Vertices + middle of edges Quadratic (2nd order polynomial)




Field calculation: 1st and 2nd order approach

Using 1st order elements: the potentials are approximated linearly and the fields derived from the potentials are constant.

Using 2nd order elements: the potentials are approximated quadratically and the fields are approximated linearly.

Element Potentials Field

1st order Linear approximation Constant 2nd order Quadratic approximation Linear approximation



7.1.3. A valid mesh: some rules to follow

Introduction Mesh construction is surely the most time consuming step in defining a

problem. To obtain a valid mesh, one needs a certain level of experience, as well as some intuition about the computation result.

General rules We can, however, establish some general rules to follow:

• The finite elements should be well proportioned. The ideal elements for a surface mesh are equilateral triangles and squares. The ideal elements for a volume mesh are regular tetrahedrons and cubes. However, thanks to the second-order transformation used, the elements can be deformed within certain limits.

• The mesh should not be unnecessarily fine. A fine mesh requires a longer computation time. One may need to compromise an accurate geometrical representation of the study domain for a shorter computation time.

To mesh a complex shape domain is not an easy task and rarely can one succeed on the first attempt. One should try to combine the available mesh tools in order to obtain a satisfactory finite element discretization.

Mesh and the physics of the problem

It is necessary to adapt the mesh to the physics of the problem, as much as possible. The mesh refinement does in fact depend on the geometrical constraints, e.g., the mesh of a very thin region, but also on the physical constraints of the problem, such as a high variation of the permeability within an element, skin depth, etc.

As a general rule, a more rapid variation of the state variable requires the use of smaller elements.

When one has some idea about the final result, one can decide on a coarse mesh in certain regions and a fine mesh in others. Analysis of the computation results may lead one to restart the computation with a new and better adapted mesh.

Thus, one should always consider the mesh while the geometry is being constructed.

Examples of physical criteria to validate a mesh

Different physical criteria may be used to validate a mesh One can verify the following points: • if the field lines present cracks in the same region, the neighboring

elements are too large • in a rotating machine, if the reaction force is different from the action

force, the mesh on the air-gap region should be refined • when dealing with field problems coupled with circuit equations, if the

current through a coil computed by different methods differs significantly, the mesh on the coil region should be refined.





7.2. Mesh strategies: mixed mesh or automatic mesh

Introduction This section refers to the mesh strategies, i.e., the two mesh possibilities

available to the user: • To mesh the entire study domain using only the automatic mesh generator. • To generate a mixed mesh, using a mesh that is the best adapted to the

physics of the problem for each domain.


• Automatic mesh or mixed mesh? • Limitations of the mixed mesh



7.2.1. Automatic mesh or mixed mesh?

Managing the constraints

The mesh building process should respect the constraints presented in table below, related to the modelled device.

Constraint Description of the constraint Managed byGeometrical To respect the geometry of the device

(interfaces between different volumes) The software

Physical To adapt the model to the physics of the problem (thin air-gap, skin depth)

The user

Two main situations

It is possible to distinguish the following two situations: • The mesh of the study domain is built using only one mesh generator (the

automatic mesh generator): this is the most common situation. The automatic mesh generator is simple, robust and easy to use. It is suitable for the majority of problems.

• The mesh of the study domain is carried out on different areas. The user should define the different areas and the appropriate mesh generators for each of them. In this case we use the term mixed mesh.

Automatic mesh

For an automatic mesh, the software completely ensures that the geometrical interfaces are respected.

To create the mesh of faces and volumes by respecting the geometrical interfaces, the algorithm of the automatic mesh generator can insert additional nodes on the faces or inside the volumes, so as to respect as much as possible the node density information assigned to the points and lines.

Mixed mesh For a mixed mesh, the user has more options to adapt the mesh to the physics

of the problem.

However, in 3D, the user may face software limitations; the conformity of the mesh on the interfaces between different domains may be a difficult task for the software to achieve (see the next section).

Mixed mesh: examples of use

When modeling electrotechnical devices, we mesh the air and volumes with complex topology with the automatic mesh generator, while the more sensitive parts (magnetic circuit, air-gap, skin depth, etc.) are generally meshed with the mapped or the extrusive mesh generator.

When modeling rotating machines, we generate an identical mesh on the faces (slots of machines, etc.), with the linked mesh generator.




The different mesh generators

A classification of different mesh generators with the type of mesh, name and advantages is presented in the table below.

Type Name Advantage

Automatic (Automatic)

The user can use this mesh in all situations (complex forms, etc.). The automatic mesh algorithm ensures low-distortion triangles and tetrahedrons. The mesh quality is controlled by the node distribution on the boundary contours.

Mapped (Mapped)

The user has full control over the number and the quality of the elements. The mapped mesh generator is used principally for meshing thin regions such as thin air-gaps, thin laminations, skin depth, etc.

General mesh generators,

always available

None (No Mesh)

The no-mesh mesh generator can be used if an internal area of the geometry should not be meshed. Example: exclusion from the study domain of a conductor with constant potential, in electrostatics problems.

Linked (Linked)

The linked mesh generator can be used to: • accelerate and parameterize the mesh of repetitive 2D

structures. This functionality is very useful for meshing motor slots.

• apply cyclic conditions on two faces (the faces should have the same number of nodes)

Specific mesh generators

using geometric

transformations Extrusion

(Extrusion) The user can perform a layered surface and volume mesh on domains obtained by extrusion.



7.2.2. Limitations of the mixed mesh

Introduction The use of different mesh generators in different areas is possible thanks to

the algorithms that ensure the global coherence of the mesh on the interfaces.

There are, however, some limitations of the mixed mesh; these are detailed below.

Constraint of mesh conformity

The mesh must conform, i.e. there must be a “concordance” or matching of elements on the interfaces between different domains.

If it is common to mix triangular and rectangular elements in 2D, mixing hexahedral and tetrahedral elements in 3D can pose certain problems.

Through automatic insertion of pyramidal elements FLUX 3D ensures the conformity of the mesh on the interface between domains meshed with hexahedrons or prisms and domains meshed with tetrahedrons. An example is shown in the figure below.




Example of non-conformity

An example of non-conformity on the interface between two domains, the first one meshed with hexadrons and the second one meshed with tetrahedrons, is shown below.

Two triangular surface elements, which are faces of two tetrahedral elements, correspond to a rectangular surface element that is a face of a hexahedron

Principle of algorithm to repair non-conformity

To ensure the conformity of the mesh, FLUX uses an algorithm to repair non-conformities between hexahedrons and tetrahedrons or between rectangular faces of prisms and tetrahedrons by inserting pyramids.

In the presence of triangular and rectangular surface elements, FLUX generates pyramids, starting from two triangular elements.

Two cases may occur: • The two tetrahedrons attached to the two triangular surface elements have

the same vertex node. In this case, the tetrahedrons can be connected to create a pyramid.

• If the two tetrahedrons do not have the same vertex node, FLUX will insert a new node in an appropriate position.

New node

The insertion of pyramids is not always possible, and there are a certain number of limitations to the algorithm to repair non-conformities.

First limitation If the rectangular mesh is too distorted, the triangular elements belonging

to tetrahedrons may cut the rectangular elements. This case is illustrated in the figure below.

In this case, FLUX 3D cannot ensure the mesh conformity.




Second limitation

The second limitation is less clear. To ensure the conformity of the mesh by inserting pyramids, FLUX3D adds a certain number of nodes. However, this algorithm does not work properly in the presence of sharp angles. This limitation is illustrated by the example below.

A simple device consisting of 3 hexahedral volumes is shown in the following figure: • Two external volumes are meshed using the mapped mesh generator • An inner volume is meshed using the automatic mesh generator

We note that in practice the mesh of this device is not possible.

The failure of the non-conformity repairing algorithm is due to the fact that the insertion of nodes to construct pyramids is not possible for this configuration.



7.3. Operation of the Mesh module: general steps

Introduction Mesh construction consists of partitioning a domain into sub-domains called

finite elements. This operation is assisted by the software, but it is not completely automatic.

Several mesh utilities permit the user to control the mesh process.


• Mesh construction process • Mesh adjustment: general information • Mesh and geometry: from one module to the other



7.3.1. Mesh construction process

Overview Mesh construction includes different steps that depend, in part, on the mesh

generators used.

Generally, it is possible to distinguish the following steps:

Step Description 1 Preliminary consideration: choice of a mesh type

• automatic mesh (single mesh generator) • mixed mesh (multiple mesh generators)

2 If mixed mesh Then definition of the different areas

- and use of generic mesh generator - or creation of user mesh generator for these different areas

3 Mesh adjustment (adjustment of the size and number of elements)

4 Mesh construction (creation of line, surface, volume elements)

5 Choice of the type of elements: 1st order or 2nd order

Mesh strategy (1 and 2)

The two first phases of mesh process are consideration phases on mesh types and mesh generators choice. For this consideration, see section 7.2 concerning mesh strategies.

Creation, mesh generator assignment (2)

This phase concern the possible creation of user mesh generators and assignment of mesh generators to the different areas.

In the case of mixed mesh, the user can: • in one hand, use the generic mesh generators (Automatic, Mapped or No

Mesh) • in the other hand, use his own mesh generators (linked or extrusion mesh

generators)

Important: In the geometry context, if the building options “with mesh” are activated during propagation and/or extrusion phases, linked and/or extrusive mesh generators are automatically created.




Adjustment and mesh (3 and 4)

Meshing and mesh adjustment are two more or less interdependent processes: • meshing (subdivision of lines, faces and volumes) is carried out by the

software • adjustment (adjustment of the size of the elements) is performed by the user

The complete process is represented in the diagram below.

Mesh lines

Mesh adjustment

Mesh faces

Mesh volumes

The detail of adjustment operations is described in the following paragraph (§ 7.3.2 “Mesh adjustment: general information”).

Choice of the type of elements (5)

This last phase of mesh process is specific to Preflux 3D. With Preflux 2D, elements created are automatically 2nd order elements.



7.3.2. Mesh adjustment: general information

Adjustment: definition

Mesh adjustment consists of adjusting the size and the number of elements.

Two types of adjustment

To adjust the mesh, the user should take into account the geometry being modeled.

The user has the option to set: • the node density around selected points, • the number and the distribution of nodes on the lines.

Information related to the node density next to selected points is information assigned to the points; we use the phrase “mesh adjustment via the points” or by the intermediate of mesh points.

Information concerning the number and the distribution of nodes on the lines is assigned to the lines; we use the phrase “mesh adjustment via the lines” or by the intermediate of mesh lines.

Principle of adjustment “via the points”

The principle of mesh adjustment “via the points” is illustrated in the example below. 5 mm1 mm

• the user imposes a length of 1 mm on the left point and a length of 5 mm on

the right point • the program subdivides the line according to this information: the first line

element in contact with the left point has a length of 1 mm and the first line element in contact with the right point has a length of 5 mm. The program arranges the nodes between the two points, following a geometrical progression.

Principle of adjustment “via the lines”

The principle of mesh adjustment “via the lines” is illustrated in the example below. 10 equidistant elements

• the user imposes the number of elements and their distribution on the line:

10 line elements, equidistant nodes. • the program divides the line according to this information.




Priorities for the lines and the points

If both lines and points are assigned mesh information, the lines have priority over points.

Example • Points P1, P2, P3 and P4:

length of line elements next to points: 2 mm

• Line Lz: geometric progression of the line elements on the line: - minimum distance: 1 mm - ratio : 1.5

Result: The information for line Lz has priority over the information assigned to points P1 and P4.

P1

P3

P2

P4

Lz Ly

Lx



7.3.3. Mesh and geometry: from one module to the other

Problematic We have presented in the chapter concerning geometry one geometry buiding

process, and we present in this chapter one mesh construction process.

In the reality, the user generally proceeds by successive steps and he could repeat several building geometry processes and several mesh construction processes. So, he is going back and forth between geometry and mesh contexts (see examples hereafter).

Example 1 For a motor description, the user could proceed as follow:

Phase Description Context 1 Geometry building of a rotor slot (Creation of

slot points and lines, building faces). Geometry

2 Preparation of slot mesh (Creation of Mesh Point and/or Mesh lines and assignment to points and lines).

Geometry Mesh

3 Meshing of the slot, visualization of surface elements and mesh adjustment. Mesh

3 Propagation of the slot and mesh informations. Geometry 4 …

In this example, the user switches from geometry context to mesh context, then go back to geometry context, …

Example 2 To facilitate the mesh of the device, the user often needs to add

supplementary points, lines, faces or volumes.

Based on these supplementary entities, the user can adjust the density of mesh nodes and control the mesh distribution between high node density areas with small elements and low node density areas with larger elements.

In this example, the user go back to geometry context, …after a phase in the mesh context…

Return to geometry context after mesh operations

Important: To go back and forth between geometry and mesh modules are authorized for non-mesh structures. If the project is meshed, geometric modifications are not allowed. To modify a meshed geometry, it’s necessary to first delete the mesh.



7.4. Mesh generators specificities and limitations

Introduction This section presents specificities (and limitations) of mesh generators trough

examples.


• Mapped mesh: 2D examples • Mapped mesh: 3D examples • Linked mesh: 2D examples • Extrusive mesh: 2D example • Extrusive mesh: 3D example



7.4.1. Mapped mesh: 2D examples

Introduction The surface mapped mesh generator is relatively powerful. However, if the

geometry of a face is very different from the square reference domain, the mesh quality may worsen and the mesh may become incoherent.

Examples of faces meshed with the mapped mesh generator are presented below.

Note that a degradation of the mesh can be observed under the following conditions: • when “the corners are no longer corners” , e.g., a circle • on faces bordered by more than four lines, if the face concavity becomes

too large; however, an exact limit for concavity is difficult to define.

Examples Examples of faces composed of four lines that are meshed with the mapped

mesh generator: • The first face is a quadrilateral. The top and bottom lines are geometrically

meshed and the mesh is perfectly propagated inside the face. • The second face is a 180-degree piece of ring. A geometric line subdivision

is used in the radial direction. The mesh is perfectly propagated inside the face.

Example The face is a disc defined by four lines. The mesh is very good except at the

four “corners” of the disc.




Examples Two examples of faces, each composed of five lines (convex face and

concave face), are presented below. For these two faces the mesh is good.

Example The face shown below is composed of twelve lines and points and it is

characterized by significant concavities. The structuration is done using the four end points on the left and on the right. The other eight vertices are angular. The resulting mesh is incorrect.

To obtain a valid mesh, this face should be subdivided, e.g., into five faces.

Example Two types of mapped mesh of a concave face bordered by six lines.

Depending on the mesh discretization, the mesh is correct or not. Subdivision of the face into two faces is recommended.



7.4.2. Mapped mesh: 3D examples

Introduction The volume mapped mesh generator is less powerful than the surface mapped

mesh generator. To get a good quality mesh, the shape of the geometry should be close to the cubic reference domain (see the 3D examples).

Some examples of volumes meshed with the mapped mesh generator are presented below. Note that a degradation of the mesh can be observed in cylindrical volumes. The mapped mesh generator does not accept volumes having cylindrical faces of 180 degrees or more. If the elements are too fine, the mesh may become incoherent.

Example Mapped mesh of a hexahedron with planar faces: The elements are of good

quality.




Examples Mapped mesh of a “tile”:

• The mesh of the first tile is not perfect, but since the deformation of the elements stays within acceptable limits, the mesh remains correct.

• The mesh of the second tile, which is finer, is densely meshed along the thickness. The elements are very distorted and the majority of those that touch the inner face are incorrect. To obtain a correct hexahedral mesh, one can either subdivide the volume, or, even better for this geometry, one can use a geometrically extruded mesh with a mapped base.

Mapped mesh of a tile: elements are correct although distorted

Refined mapped mesh of a tile: elements are incorrect because they are too

distorted



7.4.3. Linked mesh: 2D examples

Introduction Some examples of faces meshed using a linked mesh generator are presented

below.

Example Linked mesh of the stator slots of a motor.

This motor is described in detail in the tutorial: Brushless permanent magnet motor simulations in FLUX2D.

Example Linked mesh of rotor and stator slots of a motor.

This motor is described in detail in the technical paper: End winding characterization with FLUX3D.



7.4.4. Extrusive mesh: 2D example

Extrusive mesh of faces

Though developed to mesh volumes, the extrusive mesh generator can also be assigned to faces.

To obtain an extrusive mesh on faces, a prerequisite is that the face be obtained by extrusion with an existing transformation (rectilinear extrusion by translation, positive ratio affinity, or curvilinear extrusion by rotation).

Example Extrusive mesh of a quarter of circle. Extrusion of the base line by a rotation

of 90°.



7.4.5. Extrusive mesh: 3D example

Example We consider below a device consisting of eight volumes, meshed by extrusion

(extrusion by translation for the first four volumes and extrusion by rotation for the other four volumes). We constructed two different extrusive meshes, one having a triangular base, the other a rectangular base. On this mesh, we note the following: • The capability of producing a cyclical mesh • The rotational extrusive mesh can use specific elements close to the axis

(prisms, tetrahedrons, pyramids). • The direction of extrusion is unimportant.




Example A geometry composed of six volumes is presented below. These volumes are

meshed using three extrusions in different directions. We also imposed linear geometric subdivisions on four lines corresponding to the four edges of the extrusion.





7.5. Description of specific meshes, examples

Introduction To generate a valid mesh, there are:

• mesh strategies and rules that facilitate the mesh of particular geometries (thin regions, etc.)

• a certain number of rules to follow to mesh rotating and translating air-gaps.


• Mesh of thin regions: addition of lines

• Mesh of devices with skin effect

• Mesh of the translating air-gap (2D)

• Mesh of the rotating air-gap (2D)



7.5.1. Mesh of thin regions: addition of lines

Mesh of thin regions

The mesh of a thin region can be simplified by adding supplementary points and lines that are not used in the construction of regions. This is illustrated in the figure below.



7.5.2. Mesh of devices with skin effect

Mesh of skin depth: rules to follow

To obtain accurate results in skin effect problems (eddy currents, etc.), at least two elements should be used on the skin depth. The state variable actually has an exponential variation on the skin depth, but within an element, FLUX2D uses a parabolic approximation. Thus, the size of elements should be small enough that the arc of parabola can be assimilated to an exponential arc.

Computation of skin depth: recall

In magneto-harmonic problems with linear materials, the skin depth can be expressed as follows:

δρ

πµ=

f

where f is the frequency, ρ the resistivity and µ the magnetic permeability.

Choosing the mesh generator

To mesh the skin depth, elements of rectangular or hexahedral type are recommended, that is: • the mapped mesh generator (2D, 3D) • an extruded mesh generator with a mapped base (3D) The rest of the study domain is meshed using the automatic mesh generator.

2D Example A 2D example of mesh on the skin depth is shown in the figure below.

δ = skin depth

billet

magnetic circuit

inductor

Mapped mesh of skin depth {




3D Example A 3D example of mesh on the skin depth is shown in the figure below.

The most critical volumes (the volumes corresponding to the skin depth of the bar) are meshed using the extrusive mesh generator. The rest of the study domain is meshed using the automatic mesh generator (inside the bar and the surrounding air).



7.5.3. Mesh of the translating air-gap (2D)

Principle of remeshing

During the solving process, the mesh of the translating air-gap area is rebuilt for each change in the position of the moving part. The remeshing is carried out as follows.

Step Description

1 The elements of the moving part are moved by translation 2 The elements of the displacement region are either distorted or

transferred to the other end, according to the following criteria: • for a small displacement of the moving part (smaller than half

the height of an element) the elements are flat. • for a large displacement of the moving part (larger than half the

height of an element) the elements are transferred to the other end.

3 The translating air-gaps are remeshed.




Translating air-gap in 2D: additional mesh rules

Besides the usual mesh rules, some additional rules must be respected for the mesh of the translating air-gap: The moving part can be meshed with triangular or quadrangular elements, but there must be always the same number of nodes on the upper and lower edges in contact with the displacement region. The displacement region, which consists of two distinct areas, should be meshed with quadrangular elements. There must be the same number of elements across the width of the displacement region. The translating air-gap should contain only one layer of triangular elements in its thickness, and these elements should have a shape as close as possible to an equilateral triangle.

Examples of mesh

Some examples of correct and incorrect mesh of the displacement region and of the translating air-gap are illustrated in the figure below.




Advice Besides the mesh rules already presented, we are primarily interested in how

to mesh the translating air-gap. In fact, to obtain correct results it is necessary to mesh the translating air-gap correctly: • a single layer of triangular elements within the thickness • the shape of each element should be as close as possible to an equilateral

triangle. The translating air-gap is located at the interface between the fixed and the moving parts. If the mesh of these regions is locally refined, it will impose a number of nodes on the external lines of the translating air-gap, and may make it difficult to adjust the mesh in the translating air-gap. To overcome mesh constraints related to the external parts, usually it is best to construct an independent translating air-gap between the moving and the fixed parts, that is, to add supplementary layers on either side of the translating air-gap.

Step Action

1 Geometry: Construct a separate//independent translating air-gap between the moving part and the fixed part.

2 Mesh: Adjust the mesh on the boundaries of the translating air-gap

« Additional layers»

Displacement region




Displacement at constant velocity: advice

When the moving part moves at a constant velocity, the translating air-gap should be meshed evenly, depending on the displacement at each time step. The mesh of the translating air-gap is thus identical at each time step, one node replacing another node. In this way, we avoid possible mesh noise that can be reflected in the computation of the global quantities: force, etc. Thus, one should adjust the mesh on the translating air-gap according to the following rules:

• adjust the number of nodes on the edges of the translating air-gap so that the value of the triangle’s edge corresponds to the displacement of the mobile part over a time step: ∆d = v . ∆t where ∆d is the value of the triangle’s edge, v is the displacement velocity and ∆t the value of the time step.

• modify the thickness of the translating air-gap so that the triangles are equilateral: h = √3/2 . ∆d where h is the triangle height, ∆t the value of the time step and ∆d the value of the triangle’s edge.

h

∆d



7.5.4. Mesh of the rotating air-gap (2D)

Principle of remeshing

During the solving process, the mesh of the rotating air-gap is rebuilt at each change in the position of the moving part.

Rotating air-gap: additional mesh rules

In addition to the usual mesh rules, some rules must be respected for the mesh of the rotating air-gap, as follows: The rotating air-gap should contain only a single layer of triangular elements, and their shape must be as close as possible to an equilateral triangle. Some examples of correct and incorrect mesh for the rotating air-gap are illustrated in the following figure.




Advice To obtain correct results it is necessary to mesh the rotating air-gap

correctly: • only one layer of triangular elements on the thickness • the shape of the elements should be as close as possible to an equilateral

triangle. The rotating air-gap is located at the interface between the fixed part and the moving part. If the mesh of these regions is locally refined, it will impose the number of nodes on the external lines of the rotating air-gap and then it may be difficult to adjust the number and the shape of triangles in the rotating air-gap. To overcome the mesh constraints related to the external parts, usually it is best to build an independent//separate rotating air-gap in the middle of the air-gap, between the moving part and the fixed part.

Step Action

1 Geometry: Build an independent//separate rotating air-gap in the middle of the air-gap between the mobile and the fixed parts.

2 Mesh: Adjust the mesh on the boundaries of the rotating air-gap.




Rotation at constant velocity: advice

When the moving part moves at a constant velocity, the rotating air-gap should be meshed evenly, depending on the displacement at each time step. The mesh of the rotating air-gap is thus identical at each time step, one node replacing another node. In this way, we avoid possible mesh noise, which can be reflected in the computation of global quantities: torque, etc. Thus, one should adjust the mesh on the rotating air-gap according to the following rules:

• adjust the number of nodes on the boundaries of the rotating air-gap so that the value of the triangle’s edge corresponds to the displacement of the mobile part over a time step: r.θ = v . ∆t where r.θ is the value of the triangle’s edge, v the angular velocity and ∆t the time step.

• Modify the thickness of the rotating air-gap to obtain equilateral triangles: h = √3/2 . r.θ where h is the height of the triangle and r.θ the value of the triangle’s edge.

θ

r int h

r ext




FLUX® 9.10 Geometry/mesh importation: principles

8. Geometry/mesh importation: principles


• on the one hand, the different possibilities of geometry/mesh importation with FLUX and the general options for conversion

• on the other hand, the principle of importation (importation of geometry starting from geometrical files or importation of geometry starting from mesh files)


• Geometry/mesh importation: overview • Geometry importation (IGES, STEP, DXF, STL, FBD, INTER formats) • Mesh importation (NASTRAN, PATRAN, UNV Ideas formats)


Geometry/mesh importation: principles FLUX® 9.10



8.1. Geometry/mesh importation: overview

Introduction This section presents a general point of view concerning the authorized

formats for importation and the principle of conversion.


• Importation formats • Principle of conversion and options for conversion



8.1.1. Importation formats

Authorized formats

The authorized formats for importation can be divided in two categories: • geometry importation:

- in standard format: IGES, STEP, DXF, STL - in proper format: FBD, IF3 (INTER)

• mesh importation: - in standard format: NASTRAN, PATRAN, UNV

Importation formats

The various formats of geometrical files accepted by FLUX are gathered in the table below.

File format Extensions

IGES (Initial Graphics Exchange Specification) *.IGES, *.IGS STEP (Standard for Exchange of Product) *.STEP, *.STP DXF (Draw eXchange File) *.DXF STL (STereo Lithography) *.STL FBD (FLUX2D geometry) *.FBD INTER (IGES for FLUX3D) *.IF3

The various formats of mesh files accepted by FLUX are gathered in the table below.

File format Extensions

NASTRAN neutral *.NAS, *.DAT PATRAN neutral *.PAN, *.DAT UNV (UNiVersel Ideas Master Serie) *.UNV

Type of accepted file

For importation FLUX accepts only files in text format. The binary files are not accepted.

Attention: It is not possible to import the assembly file of several IGS files (*_ASM.IGS).

Multiple importation

Multiple importation is available. FLUX is able to import the files with different formats (DXF, STL, etc) in the same project.



8.1.2. Principle of conversion and options for conversion

Principle of conversion

Importation is an operation that convert the initial file entities into FLUX entities (geometric entities of Point, Line, … type).

Options for conversion

To perform the data conversion, different options are proposed to the user.

These options are of two types: • general options, available for all formats • particular options, specific to the format

Only the general options are described in this section.

General options for conversion

The general options for conversion available for all formats are following: • choice of a coordinate system: to place the imported geometry in the FLUX

project • choice of the unit: to choose the units of the device dimensions • choice of precision: to define the minimal distance enabling to distinguish

two points

These options are detailed in the following blocks.

Coordinate system

At the moment of importation, a coordinate system is created in the FLUX project with the name XXXi (where XXX = extension corresponding to the imported format). This coordinate system coincides with the principal coordinate system XYZ1. Then the user can displace the device (for example, with respect to the infinite box, etc.) by modifying the position of the imported coordinate system.

At the moment of importation, the user can position the device in one of the following coordinate systems: • the proper coordinate system of the device: XXXi • a predefined coordinate system : XYZ1, Z_ON_OX, Z_ON_OY • an user coordinate system: …




Length unit The device is described in proper units in the initial file, but the information

about the length unit is not present in this file.

At the moment of importation, the user can choose a length unit as follows: • by default: meter • another possibility: meter * conversion factor

The conversion factor is the ratio between the length unit chosen by the user and the FLUX length unit, which is the meter.

Examples of conversion are presented in the table below.

If the entities in the initial file are in …

and the conversion factor is equal with …

the unit in the FLUX project is …

Meter 1 Meter Millimeter 0.001 Millimeter

Micron (micrometer) 10-6 Micron

Caution: The length unit previously chosen is automatically assigned to the imported coordinate system XXXi.

If the device is imported in another coordinate system, the user must assure that the length unit of this coordinate system is compatible with the importation length unit.

Precision The absolute precision is the minimum distance between two points of the

geometry (or between two nodes of the mesh) from which the two points (or the two nodes) of the initial file are represented by only one point in the FLUX project.

Absolute precision

Initial file:distance between 2 points (or nodes)

FLUX file:1 point

The absolute precision is: • either imposed by the user • or automatically computed by FLUX (automatic precision)




Automatic precision

The automatic precision, quantity automatically computed by FLUX, is obtained by means of the following formula: Absolute precision = Relative precision * Diagonal where: • Relative precision, also called relative epsilon, is a coefficient independent

of the length unit, fixed to 10-5 for the importation • Diagonal is the distance between two faraway points of the box

surrounding the device (see the figure below)

3D geometry 2D geometry



8.2. Geometry importation (IGES, STEP, DXF, STL, FBD, INTER formats)

Introduction This section deals with the importation of geometry starting from geometrical

files.

The formats which enable the geometry importation are following: • standard formats:

- Initial Graphics Exchange Specification (extensions: *.IGES, *.IGS) - Standard for Exchange of Product (extensions: *.STEP, *.STP) - Draw eXchange File (extension: *.DXF) - STereo Lithography (extension: *.STL)

• proper formats - FLUX2D geometry (extension: *.FBD) - IGES for FLUX3D (extension: *.IF3)

Interest of FLUX for IGES / STEP formats

The geometry importation from a file in IGES / STEP standard format enables the consideration by the FLUX projects of complex geometries with uneven surfaces.

These surfaces cannot be directly built with the FLUX tools.


• Process of geometry importation • Stage of conversion • Stage of geometry checking: concept of geometric defect • Stage of geometric defects correction / geometry simplification • Geometry importation: strategies



8.2.1. Process of geometry importation

Introduction The importation of a geometry from a file is an operation that consists in

converting the geometry of the initial file (specific to the format) into FLUX entities (geometric entities of Point, Line, …type).

Question It is important to note that in FLUX, the user should build the geometry

without defects. A defect, in the FLUX sense, is an error of the geometrical construction of intersection of lines type, of superposition of points type, etc.

If there are geometrical defects in the origin file (intersection of lines, superimposed points, etc.), these can hinder and also block the process of geometry building: impossibility of building faces and/or volumes.

So, after the geometry importation, it is necessary that complementary actions should be taken in order to search (identify) and correct the geometric defects.

Importation process

The process of importation is a process involving the three stages briefly describing in the table below and detailed in the following paragraphs.

Stage Description

1 Conversion 2 Geometry checking / search geometric defects 3 Correction of geometric defects

and/or geometry simplification



8.2.2. Stage of conversion

Introduction The first stage of importation is a stage of conversion of the imported

geometry into the FLUX format.

Operation principle

The principle of operation of the importation is following: all the geometric entities of the initial file (specific to the standard and proper formats) are converted into the FLUX format (geometric entities of type Point, Line...) in the final file.

Conversion of entities

The entities of the initial file are read and converted into the FLUX entities. The summary table is presented below.

The file in the format

…

contains entities CAD

… which are converted into FLUX entities …

points points defined by parameterized coordinates lines lines of type:

• segment defined by extremity points • arc defined by origin, intermediary and

extremity points • curve (for the unspecified lines)

IGES / STEP

faces faces of type: • automatically defined by plane, cylindrical

or conical surfaces • uneven type, defined by any kind of

surfaces POINT points defined by parameterized coordinates LINE lines of segment type defined by extremity

points POLYLINE N lines of segment type ARC, CIRCLE

lines of arc type defined by origin, intermediary and extremity points

DXF

3DFACE faces of automatic type, with triangular shape, defined by a plane surface

VERTEX points defined by parameterized coordinates STL FACET faces of automatic type, with triangular shape,

defined by a plane surface




Conversion of entities (continued)


…

contains entities CAD

… which are converted into FLUX entities …

points points defined by parameterized coordinates lines lines of type


extremity points faces automatic faces geometric parameters

geometric parameters

FBD

regions regions points points defined by parameterized coordinates

IF3 lines lines of type:


extremity points



8.2.3. Stage of geometry checking: concept of geometric defect

Introduction The second stage is the geometry checking.

This stage is the stage of a research (identification) of the geometric defects; as to the correction, this will be carried out in the following stage (stage 3).

Before describing the modes of defects search, the different defect types are described in the following blocks.

Geometric defects

The geometric defects can hinder or block the geometry building process.

The following can be therefore discerned: • blocking defects (intersections and superimposed entities):

these defects must be identified and corrected before building the geometry in FLUX.

• non-blocking defects (very small lines and faces, wires not closed, …): these defects do not impede the geometry building in FLUX, but they can influence in a negative manner the quality of the geometry building and/or the meshing

The geometric defects are presented in the table below.

Defect Example (or type) Consequence

blocking

• intersection of type: - line-line - line-face - face-face*

• superposition of type: - confused points - superimposed lines

• entities of small dimensions: - abnormal line - abnormal face

building of the faces and volumes impossible

• entities of small dimensions: - abnormal line (user epsilon) - abnormal face (user epsilon)

difficulties of meshing non-

blocking • open wire missing face

*In the next figure, the faces building after the importation of the geometry will generate the intersection of the faces. This type of defect is not identified by FLUX in the Geometric defect entity, but it is blocking for the further volumes building. The connecting the points P1 and P2 by a new line before the faces building enables to avoid the intersection of the faces.

P1 P2




Defects research modes

The research of the geometric defects can be carried out in two ways: • by type of defect (described as research by type) • for the assembly of types of defects (described as global checking of the

geometry)

Research result Whatever the research mode, the result is the following:

• FLUX creates a geometric entity of the Geometric defect type for each defect found (this entity contains the information about the defect localization: number of concerned points, lines or faces)

• FLUX highlights this entity in a graphic window (specific display)



8.2.4. Stage of geometric defects correction / geometry simplification

Introduction The third stage is the stage of correction of geometric defects and/or

geometry simplification.

Correction principle

The principle of correction proposed by FLUX for the various types of geometric defects is presented in the tables below.

Defect of the superposition

type Principle of correction

Confused points ⇒ Suppression of a point Superimposed lines

P2

P4 P3

⇒

Cutting of the lines

L2 P4 P3

P1 P2

L1 L1 L3

P1

L2

Defect of the intersection type Principle of correction Intersection of two lines

P4

P3

L1

P1

L2

P2

⇒

Cutting of the lines

L12 L11

L22

L21

P4

P1

P2

P3

P5

Intersection of a line and a face ⇒ Correction is to be made by the user

Defect of the type Principle of correction Line abnormal

(value fixed by the user) L2 L1

L1

L2

⇒

Removal of the L2 line by fusion of the lines L1 and L2

L1

L1

Face shorter than ...

(value fixed by the user) F1L1

L2

⇒

Removal of the F1 face by confusion of the lines L1 and L2

L1




Defect of the type Principle of correction

Open wire P2 P1 L1

⇒

Closing of contour by prolongation of the L1 line

P1 L2

L2 L1

Simplification principle

The principle of simplification proposed by FLUX consists to remove some lines and points and thus “to reduce” the geometry. Simplification is expected only for the lines of the segment type and arc of circle type.

The principle of simplification is presented in the table below.

Geometry of type Principle of simplification

Segments located on the tangent of the straight lines

P4P3 P1 P2 L3L1 L2

⇒

Removal of the lines L2 and L3 and suppression of the points P2 and P3 by fusion of the lines L1, L2 and L3

P4P1 L1

Arc of circle having the same curve angle

L1 P2 P1

P3 P4

Removal of the lines L2 and L3 and suppression of the points P2 and P3 by fusion of the lines L1, L2 and L3

P1 P4

L1

L2 L3




Algorithms of automatic correction / automatic simplification

To facilitate the process of correction, the algorithms of automatic correction / automatic simplification are proposed. They are presented in the table below.

The algorithm of … enables the correction …

automatic correction of all blocking defects (superimposed entities and intersections)

automatic simplification of all defects of type: abnormal lines

Note: These algorithms are planned especially for the 2D geometry, the result in 3D is not guaranteed.

Manual correction

To correct the other defects the user must carry out a manual correction with the tools presented in the table below. The use of these various commands is detailed in section “Correction of geometric defects” of chapter “Geometry/mesh importation: software aspects”.

To correct the defects

of type ... the user should ...

Intersection of lines Superposition of lines

Cut line on a point Cut line on intersection

Abnormal line Abnormal face

Decrease absolute precision by reducing relative precision (relative epsilon)

Abnormal line (user epsilon) Fuse lines

Abnormal face (user epsilon) Confuse lines

Open wire Extend line to point Extend line to line



8.2.5. Geometry importation: strategies

Introduction Although it is possible and necessary to correct the geometric defects after

importation, it is preferable to prepare the initial file so that the operations of correction in FLUX are minima.

The checking of the geometry and the correction of possible geometric defects are essential.

Prepare the initial file

To prepare the initial file in general way: • define the points, lines, faces, … by respecting the characteristics of the

FLUX geometry building module • remove the intersections of lines, lines and faces, the superposition of faces,

… The characteristics of geometry building module (description: the authorized shapes of faces and volumes, prohibited intersections and superimposed entities, …) are given in chapter “Geometry: principles”.

Constraints of FLUX software

It is not possible to perform the following operations in an imported geometry (containing lines of list edges type and faces of list facets type): • modify the imported faces/lines • propagate/extrude the imported faces/lines • mesh the faces/volumes using mapped mesh generator

Capabilities of FLUX software

It is possible to perform the following operations in an imported geometry: • build the faces/volumes • mesh the faces/volumes using automatic mesh generator



8.3. Mesh importation (NASTRAN, PATRAN, UNV Ideas formats)

Introduction This section deals with the importation of geometry starting from mesh files,

named the mesh importation.

The standard formats which enable the mesh importation are following: • UNiVersel Ideas Master Serie (extension: *.UNV) • NASTRAN neutral (extensions: *.NAS / *.DAT) • PATRAN neutral (extension: *.PAN / *.DAT)

Interest The importation of a geometry starting from mesh file enables the

consideration by the FLUX projects of complexes geometries with uneven surfaces.

These surfaces cannot be directly built with the FLUX tools.


• Process of mesh importation • Stage of conversion • Stage of fusion • Stage of positioning • Mesh importation: strategies



8.3.1. Process of mesh importation

Introduction The importation of a geometry starting from mesh file is an operation which

enables the building of the device geometry based on mesh information of an initial file. This approach enables the introduction in FLUX projects of uneven surfaces in the form of “cut surfaces”, but has the disadvantage of generating an important number of geometric entities (volumes, faces, lines). As consequence, the result of the mesh file conversion is not always compatible with the requirements of FLUX analysis (for example, the use of sliding cylinder, …).

At the moment of mesh importation (or right afterwards) additional operations are necessary, in order to simplify and adjust the imported data.

Importation process

The mesh importation process involves three stages, briefly described in the table below and detailed in the next paragraphs.

Stage Description

1 Conversion 2 Fusion of the multiples faces and lines coming from the mesh

importation (facets and edges) 3 Positioning of the faces on a reference plan/cylinder



8.3.2. Stage of conversion

Introduction The first stage is a stage of conversion of the mesh entities into geometric

entities.

Volume element: reminder

In FLUX, a volume element of the mesh is characterized by vertexes, edges and facets, as shown in the next figure

side

edge

vertex

Principle of conversion

The principle of conversion shown in the scheme below is the following: all the vertexes, edges and facets of volume elements of initial file are converted into points, lines and faces in the final file.

Importation in FLUX

1 square face meshed with 6 elements

i l i

6 faces, 12 lines, 7 points

The group concept, regrouping volume elements having the same material in the initial file, enables the creation of volumes in the FLUX project.

Conversion of entities

The entities of the initial file are read and converted into FLUX entities, as presented in the table below.


…

contains entities CAD …

which are converted into FLUX entities …

nodes points defined by parameterized coordinates

line elements lines of edges list type face elements faces of facets list type

NASTRAN / PATRAN

/ UNV groups: component or material

volumes

Structure of data

In FLUX, the geometric entities resulting from the mesh importation differ from “standard” geometric entities: • the faces resulting from mesh importation are faces of facets list type • the lines resulting from mesh importation are lines of edges list type



8.3.3. Stage of fusion

Introduction Following the importation, the geometry of the imported device has multiple

lines and faces deriving from multiple facets and edges of the initial file.

The second stage is the stage of fusion (regrouping of the entities), which enables the reduction of number of lines and faces, and facilitates their handling, as well as the visualization of the device.

Fusion of faces: use

Although strongly advised, the fusion of faces/lines is optional. This operation becomes compulsory for the faces in the cases presented below.

If … The fusion …

kinematic coupling of dissociation faces (sliding cylinder, boundary of mobile mechanical set and compressible mechanical set)

symmetry and/or periodicity planes of faces located on these planes

… is compulsory

Concept of fusion

We call fusion of faces/lines the operation of regrouping faces/lines to form the main faces/lines of the device geometry.

Principle of fusion of faces and data structure

The principle of fusion of faces is shown on the scheme below. During fusion all faces belonging to the same surface are regrouped in one face.

Fusion

Set of faces that resultsfrom facets of the initial

file

A single face thatcontains many

facets

The faces resulting from mesh importation are faces defined by a list of facets. • Before the fusion of faces:

every face (of facets list type) contains a single facet • After the fusion of faces:

every face (of facets list type) contains many facets




Regrouping surface and angle of fusion

The surface of regrouping is defined by the user, using an angle named angle of fusion. All adjacent faces whose angle is less than the fusion angle are regrouped in a single face (See figure of example below).

Example : Three adjacent faces are regrouped in a single face with a fusion angle α

Angle [ ]α;0°∈

Angle [ ]α;0°∈

The regrouping surfaces can be of different shapes (plane, cylindrical, …) and depend on the chosen value of fusion angle as follows: • for an angle of small value (between 0 and 1°), the regrouping surface is a

planar surface • for a larger angle, the regrouping surface can be of any shape

Precaution So that the simplified geometry approaches with more real geometry, it is

necessary to take some care as for the choices of an angle of fusion, the risk being to gather faces, which should remain separate.

In general, it is advised to comply with the following rule: • start with an angle that is inferior or equal to 1° - to identify the plane faces • gradually increase the value of the angle - to identify the others faces

Attention The fusion process does not create even surfaces. The regrouping surface is

an uneven surface, although this surface looks like an even one.

And for the lines …

The principle of lines fusion is the same with the one of faces fusion. It is illustrated in figure below.

Fusion

Set of lines that resultsfrom edges of the initial

file

A line thatcontains many

edges




Rules of fusion Two faces (lines) can be regrouped if they belong to same volumes (faces).

The mesh importation of a quarter cylinder before and after the fusion of faces and lines is shown in figure below.

Geometry created in FLUX starting from an imported mesh

Geometry in FLUX after fusion of faces and lines



8.3.4. Stage of positioning

Introduction After importation of mesh and simplification of geometry, the quality of the

faces obtained starting from mesh data can be unsatisfactory for the FLUX further operations (see examples below). In this case, it is necessary to adjust the geometry.

Examples: • If we want to impose the condition of periodicity on two faces which

theoretically form an angle of 60°, but in reality the imported faces form an angle of 59.9999°, it is necessary to adjust the geometry in such way that the real angle between the two faces to be 60°.

• If we want to use the sliding cylinder entity and if the face corresponding to the surface of dissociation not be really carried by a cylindrical surface, it will then be necessary to adapt the consequently geometry.

Positioning of faces: use

The positioning of the faces is optional but becomes compulsory for the faces in the following cases:

If … the positioning …

kinematics coupling of dissociation faces (sliding cylinder, boundary of mobile mechanical set and of compressible mechanical set)

Symmetry and/or periodicity planes of faces located on these planes

… is compulsory

Concept of positioning

We call positioning of a face on a plan or on a cylinder the operation that consists in projecting the face on a reference plan or cylinder, defined by the user.

The positioning is not intended to orient differently the plans with respect to imported geometry, but to homogenize this geometry in order to ensure a good FLUX further operation.

Principle of positioning

The positioning of a face F on a surface S means the projection of points, nodes of F on S, the edges follow the movement. Thus, the use of positioning of faces by their displacement with many degrees with respect to the initial geometry can results in a geometry deformation.

Many successive displacements can emphasize the deformation of the geometry even if we return to an arrangement conform to the imported geometry.



8.3.5. Mesh importation: strategies

Strategies of mesh importation

Previous to mesh data importation is important to choose a strategy for the importation. It is possible: • to import a complete geometry of the device, i.e. all its components, the

including box and the complete mesh of the study domain • to import the geometry and the mesh of a only one component or of a part

of the device and to complete the description of geometry and mesh in FLUX.

The further steps of the project depends on the chosen strategy.

Strategy 1 The first strategy consists in importing the whole study domain. The process

of importation can be presented as follows:

Stage Description 1 Preparation of initial file in the origin software:

• full description of the device geometry • addition of an air region or of a box including the device • meshing of study domain

2 Data importation into FLUX by using the option: • with mesh (mesh data importation)

3 Simplification of file: • fusion of faces/lines

4 Direct passage to physics

Strategy 2 The second strategy consists in importing a specific meshed part of the

device. The process of importation can be presented as follows:

Stage Description 1 Preparation of initial file in the origin software CAD (ex. rotor):

• description of the geometry of the device part • mesh of this part

2 Data importation into FLUX by using the option • without mesh

3 Simplification and adjustment of file: • fusion of faces/lines • positioning of faces

4 Building in FLUX of the rest of the device geometry (ex. stator) : • geometrical construction of other device parts • construction of faces and volumes • mesh of the whole computation domain

5 Direct passage to physics

Important: The device parts, added by FLUX, do not have to touch the imported geometry (imported parts).




Constraints of FLUX software

It is not possible to perform the following operations in an imported geometry containing lines of list edges type and faces of list facets type: • modify the imported faces/lines • propagate/extrude the imported faces/lines • modify the mesh of imported objects; the initial mesh is entirely preserved

Capabilities of FLUX software

It is possible to perform the following operations in an imported geometry: • build the faces/volumes • mesh the faces/volumes using automatic mesh generator

Preparation of initial file

During the preparation of the initial file: • you must verify if the mesh is non-conform (ex: the addition of two parts

separately meshed is forbidden) • when the periodicity is present, you should perform an identical mesh on

the faces concerning the periodicity

Attention: A non-conform mesh in the initial file may generate intersections that cannot be removed.


Documents

[F91] Users Guide Volume 1