Manual, System Coupling Users Guide

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Tutorial: Oscillating Plate with Two-Way Fluid-Structure Interaction

In this tutorial you will learn how to solve a Fluid-Structure Interaction (FSI) case. You will model struc-

tural deformation in a fluid using System Coupling to coordinate the ANSYS Mechanical and ANSYS

Fluent solvers.

DetailsFeatureComponent

Transient StructuralAnalysis SystemsANSYS Workbench

Fluid Flow (Fluent)

System CouplingComponent Systems

Defining new materialsEngineering Data

ImportGeometryDesignModeler

MeshingMechanical

Defining the physics

Named Selections

Coupled analysis restart

Coupled analysis batch

execution from command

line

MeshingMeshing

Defining the physicsANSYS Fluent



execution from command

line

Defining the couplingSystem Coupling



execution from commandline

VectorPlotsCFD-Post

Animation

This tutorial includes:

Overview of the Problem to Solve

Creating the Project

Optional: Preparing for a Command-line Run

Adding Analysis Systems to the Project

Adding a New Material for the Project

Adding Geometry to the ProjectDefining the Physics in the Mechanical Application

79Release 16.0 - © SAS I P, Inc. All rights reserved. - Contains proprietary and confidential information

of ANSYS, Inc. and its subsidiaries and affiliates.


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Setting up your Fluid Analysis

Defining and Running the Coupling in the System Coupling Application

Viewing Results in CFD-Post

Setting Up and Executing a Coupled Analysis Restart from Workbench

Executing the Coupled Analysis from the Command Line

Note

In the main flow of the tutorial, you use the user interface to completely solve the simulation.

However, at a series of points during the tutorial you have optional instructions that produce

files that will enable you to solve the simulation from the command line. The steps related

to this are:

1. Optional: Preparing for a Command-line Run (p. 82)

2. Preparing for a Command-Line Run of the Structural System (p. 90)

3. Preparing for a Command-Line Run of the Fluent System (p. 97)

4. Preparing for a Command-Line Run of the System Coupling System (p.100)5. Executing the Coupled Analysis from the Command Line (p. 105)

If you do not want to solve the simulation from the command line, you may ignore those

steps.

Overview of the Problem to Solve

This tutorial uses an example of an oscillating plate within a fluid-filled cavity to demonstrate how to

set up and run a simulation involving a two-way coupled analysis in ANSYS Workbench.

A thin plate is anchored to the bottom of a closed cavity filled with fluid (air), shown in Figure 12: Di-

mensions of the oscillating plate case (p. 80). There is no friction between the plate and the side of the

cavity. An initial pressure of 100 Pa is applied to one side of the thin plate for 0.5 s to distort it. Once

this pressure is released, the plate oscillates back and forth to regain its equilibrium, and the surrounding

air damps this oscillation. You will simulate the plate and surrounding air for a few oscillations to be

able to observe the motion of the plate as it is damped.

Figure 12: Dimensions of the oscillating plate case

Release 16.0 - © SAS I P, Inc. All rights reserved. - Contains proprietary and confidential informationof ANSYS, Inc. and its subsidiaries and affiliates.80



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To simulate this case, you will set up a two-way Fluid-Structure Interaction (FSI) analysis. You will

model the motion of the oscillating plate using the Mechanical application’s Transient Structural

analysis system. You will model the motion of the fluid in the closed cavity using the Fluent application’s

Fluid Flow (Fluent) analysis system. The two analyses are solved at the same time with the System

Coupling system coordinating the solution process as well as the data transfers between the two ana-

lysis systems.

The two-way coupling involves two data transfers:

• Force data from the motion of the air is received by the Transient Structural analysis system as it solves

the structural behavior over time.

• Displacement data from the motion of the plate is received by the Fluid Flow (Fluent) analysis system as

it solves the fluid behavior over time.

The oscillation of the plate is dependent on time, and so you need to choose appropriate time values

for the coupled transient analysis:

• Time duration is the total time observed in the analysis. In this analysis, you will set the time duration to be

10 s, which is enough time to observe the plate oscillating a few times. With this time duration, you will not

model the full damping back to the plate’s equilibrium. When setting up a transient analysis, make sure that

you choose a time duration that will allow you to observe the behavior of interest in your system.

• Time step is the size of the time increments that you are solving within your transient analysis. In this ana-

lysis, you will set the time step to be 0.1 s, which is fine enough to observe the oscillations to a reasonable

degree. When setting up a transient analysis, make sure you choose a time step that works for the physics

you are solving. Too large a time step will miss behavior of the system, and too small a time step will be

computationally expensive.


Create the project by setting up Workbench and importing the project files:

1. Start ANSYS Workbench:

• To launch ANSYS Workbench on Windows, click the Start menu, then select All Programs > ANSYS 16.0

> Workbench 16.0.

• To launch ANSYS Workbench on Linux , open a command line interface and enter the path to runwb2.

For example:

~/ansys_inc/v160/Framework/bin/Linux64/runwb2

The Project Schematic appears with an Unsaved Project. By default, ANSYS Workbench is configured

to show the Getting Started dialog box that describes basic operations in ANSYS Workbench. Click

the [X] icon to close this dialog box.

2. Create a directory where you will store your project (this is your working directory). For example, under

My Documents, create a directory named SystemCouplingOscillatingPlate.

3. Select File > Save or click Save .

4. Select the path to your working directory to store files created during this tutorial.





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5. Under File name, type SystemCouplingOscillatingPlate and click Save.

The project files and their associated folder locations appear under the Files view. To make the

Files view visible, select View > Files from the main menu of ANSYS Workbench.

6. This tutorial uses the geometry file,oscillating_plate.agdb, for setting up the project. To accesstutorials and their input files on the ANSYS Customer Portal, go to http://support.ansys.com/training .

Copy the supplied geometry file, oscillating_plate.agdb, to the user_files directory

that is in the SystemCouplingOscillatingPlate_files directory.

By working with a copy of the geometry file in your working directory, you prevent accidental

changes to the original geometry file.

Optional: Preparing for a Command-line Run

This tutorial runs from within Workbench. However, you also have the option of taking files created

from applications running in Workbench and performing a second system coupling run from a commandline. If you want to try this alternative, follow the instructions below to prepare the locations where this

second system coupling run will be performed. As you work through the tutorial in Workbench, you

will be prompted to add source files from the applications running in Workbench to the directories you

create here.

To prepare a directory structure for executing the analysis from a command line:

1. Create a high-level directory named SystemCouplingOscillatingPlate_CmdLine.This directory

should be a sibling to SystemCouplingOscillatingPlate.

2. In the SystemCouplingOscillatingPlate_CmdLine directory, create subdirectories within which

the Mechanical APDL, Fluent, and System Coupling service executables will be run. Name these subdirect-ories: Structural_CmdLine,FluidFlow_CmdLine, and Coupling_CmdLine.


You are doing a two-way FSI analysis by coupling two analysis systems: a Transient Structural system

and a Fluid Flow (Fluent) system. You will use the System Coupling system to couple the other two

systems and to coordinate the solution execution.

To add these three systems to your Workbench project:

1. From the Analysis Systems toolbox located on the left side of the ANSYS Workbench window, select the

Transient Structural template. Double-click the template, or drag it onto the Project Schematic to create

a standalone system.

A Transient Structural system is added to the Project Schematic, with its name selected and ready

for renaming.

2. Type in the new name,Structural, to replace the selected text. In this tutorial,“Structural system” will

be used to refer to the Transient Structural system.

If you missed seeing the selected text, right-click the first cell in the system and select Rename

from the context menu. You will then be able to edit the name.




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3. Drag a Fluid Flow (Fluent) analysis system on top of the Structural system’s Geometry cell (A3) and drop

it there.

A Fluid Flow (Fluent) system, coupled to the Structural system, is added to the Project Schematic.

This Fluid Flow (Fluent) system is connected to the Structural system through the Geometry cell

(A3 to B2), and so both of these systems will share the same geometry.

4. Change the name of this system to Fluid. In this tutorial,“Fluid system” will be used to refer to the

Fluid Flow (Fluent) system.

5. Expand the Component Systems toolbox, drag a System Coupling system and drop it to the right of

the Fluid Flow (Fluent) system.

6. Drag the Structural system's Setup cell (A5) and drop it on the System Coupling system’s Setup cell (C2).

7. Drag the Fluid system's Setup cell (B4) and drop it on System Coupling system’s Setup cell (C2). Now

all three systems are connected for a two-way FSI analysis.

8. Save the project.

The Project Schematic should appear as shown in Figure 13: System Coupling of Transient Structural

and Fluid Flow (Fluent) Systems (p. 83).

Figure 13: System Coupling of Transient Structural and Fluid Flow (Fluent) Systems

The Structural and Fluid systems have various cells. The icons on the right side of each cell provides

visual indications of a cell's state at any given time. In your current Project Schematic in Workbench(shown in Figure 13: System Coupling of Transient Structural and Fluid Flow (Fluent) Systems (p. 83)),

most cells appear with a blue question mark ( ), indicating that cells need to be set up before continuing

the analysis. As these cells are set up, the data transfer occurs from top to bottom. See Understanding

Cell States for a description of various cell states.

Now that your project systems are in place, you can start working through your analysis. Your current

project systems enables you to perform your analysis by:

• adding a new material,

• sharing the geometry,

• setting up the physics in the Structural system,





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• setting up the physics in the Fluid system,

• defining and running the coupling in the System Coupling system, and

• viewing the results in CFD-Post.

Adding a New Material for the Project

In the Project Schematic, the Structural system’s Engineering Data cell (A2) appears in an up-to-date

state because default material is already available for the project. You will use material for the oscillating

plate that is not in the default material available, and so you need to update this cell by adding this

new material to the Engineering Data.

The case requires a new material with properties that allow it to oscillate when pressure is applied. You

will create a new material named Plate, define its properties to be suitable for oscillation, and set it as

the default material for the analysis.

1. On the Project Schematic, double-click the Engineering Data cell (A2) in the Structural system.

Engineering Data opens in a new tab in Workbench. The Outline and Properties views are among

the views that appear.

2. In the Outline of Schematic A2: Engineering Data view, click the empty row at the bottom of the table

to add a new material for the project.Type in the name Plate.

When you click away from that cell, Plate is created and appears with a blue question mark, indic-

ating that its properties need to be defined.

3. From the Toolbox on the left, expand Physical Properties. Select Density and drag it onto the cell con-

taining Plate (A4) in the Outline of Schematic A2: Engineering Data view. If the toolbox is not visibleby default, select View > Toolbox to make it visible.

Density is added as a plate property in the Properties of Outline Row 4: Plate view, as shown in

the following figure.




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4. In the Properties of Outline Row 4: Plate view, set the Value of Density (B2) to 2550 kg m^-3. Do not

type in units.

5. In the toolbox under Linear Elastic, drag Isotropic Elasticity onto Plate (A4) in the Outline of Schematic

A2: Engineering Data view.

Isotropic Elasticity is added as the plate property in the Properties of Outline Row 4: Plate view.

6. In the Properties of Outline Row 4: Plate view, expand Isotropic Elasticity by clicking the plus sign.

Now set Young’s Modulus to 2.5e06 [Pa] and Poisson’s Ratio to 0.35. Do not type in units.

The desired plate data is created and is available to the remaining cells in the Structural system.

The next step is to set Plate as the default material for the analysis as outlined below:

1. In the Outline of Schematic A2: Engineering Data view, under Material, right-click Plate (A4) and select

Default Solid Material For Model.

2. From the main menu, select File > Save to save material settings to the project.

3. Close the Engineering Data tab to return to the Project Schematic.

Adding Geometry to the Project

You will add geometry to your project by importing an existing DesignModeler file. Once you add the

geometry, it will be shared between the Structural and Fluid systems because you have connected their

geometry cells in the Project Schematic. All of the geometry parts have to be unsuppressed at this point

in your project so that they are available for use later in the Structural and Fluid systems.

1. On the Project Schematic, right-click the Structural system’s Geometry cell (A3) and select Import

Geometry > Browse.



Adding Geometry to the Project


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2. In the Open dialog box, browse to your working directory, select SystemCouplingOscillating-

Plate_files > user_files > oscillating_plate.agdb from your working directory, and click

Open.

3. In the Structural system, double-click the Geometry cell (A3) to edit the geometry using DesignModeler.

The DesignModeler application opens in a separate window.

4. In DesignModeler’s Tree Outline on the left, expand the branch 2 Parts, 6 Bodies to see all of the bodies

that compose the geometry. The one solid body is listed, and under Part are the five fluid bodies. Ensure

that all of these bodies are already unsuppressed (they should all have small green check marks).

5. The geometry is set up for the project. Save any changes by selecting File > Save Project from the main

menu in DesignModeler, and then select File > Close DesignModeler to return to the Project Schematic.

The updated geometry is now available for both the Structural and Fluid systems.

Later in the tutorial, when you generate the structural mesh, the fluid bodies will first be suppressed.Similarly, when you generate the fluid mesh, the solid body will be suppressed. You will suppress these

bodies from within the Mechanical and Meshing applications, so no further changes are needed in

DesignModeler.

Note

Because the Structural system’s Geometry cell (A3) shares its content directly with the Fluid

system’s Geometry cell (B2), you can edit the geometry only through the Structural system’s

Geometry cell (A3).

Defining the Physics in the Mechanical ApplicationIn the Mechanical application, you are setting up the structural analysis and defining the coupling inter-

face. You will not solve the structural analysis from the Mechanical application because you will use

the System Coupling system to solve both structural and fluid systems at the same time.

When setting up your own two-way coupled analysis, it is a best practice to set up and solve the

structural analysis within the Mechanical application before continuing with your coupled analysis. If

issues occur within your structural system, the isolated analysis is easier to troubleshoot than the more

complex coupled analysis.

The structural Geometry cell (A3) is up-to-date, and so you start your setup by generating the structural

mesh. This section describes the step-by-step definition of the structural physics:Generating the Mesh for the Structural System

Assigning the Material to the Geometry

Setting the Basic Analysis Values

Inserting Loads

Preparing for a Command-Line Run of the Structural System

Completing the Setup for the Structural System

Generating the Mesh for the Structural System

Generate the mesh for the Structural system directly in the Mechanical application:




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1. On the Project Schematic, double-click the Structural system’s Model cell (A4) to open the Mechanical

application.

The Mechanical application opens in a separate window.

2. In Mechanical’s Outline on the left, expand Geometry to see the two geometries, solid and Part.

3. For the structural analysis, you need to generate the mesh for only the solid body.To do this, you need

to first suppress the Fluid bodies.

Right-click the Part geometry (which contains all of the fluid bodies), and select Suppress Body.

The fluid bodies are now suppressed and their status changes to an x mark. You now will see only

the solid body in the Graphics view. Click Zoom to Fit to view the entire model in the Graphics

view.

4. You will define the mesh by marking divisions on the edges of the solid.These divisions will be used as

guides for the mesh creation:

a. Click Edge .

b. Click an edge that lies parallel to the X axis.

c. In the Outline, right-click Mesh and select Insert > Sizing.

d. Beside Type, select Number of Divisions from the drop-down menu.

e. Beside Number of Divisions, select 1.

5. Repeat steps a to d to create 10 divisions on an edge that is parallel to the Y axis and 4 divisions on an

edge that is parallel to the Z axis. To summarize:

Number of DivisionsEdge Direction

1X axis

10Y axis

4Z axis

6. In the Outline, right-click Mesh and select Generate Mesh from the shortcut menu.

A hex mesh is generated on your solid body.

Assigning the Material to the Geometry

When you defined the Plate material, you set it to be the default for your solid body. In the Mechanical

application, you can see that this material is set correctly.

1. In the Mechanical’s Outline on the left, select Project > Model > Geometry > solid.

2. In the Details of “solid”, ensure that Material > Assignment is set to Plate. Otherwise, click the material

name and use the arrow that appears to make the appropriate change.



Defining the Physics in the Mechanical Application


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You now need to set up information about the transient analysis’ time steps, which are the basic ana-

lysis values needed for the transient structural analysis.

The time duration (10 s) is chosen so that the plate oscillates a few times during the analysis. A singlesubstep is used per coupling iteration. The coupling step size of 0.1s (which is also the size of the iter-

ations) will be defined later in System Coupling.

These time settings are dependent on the physics that you are observing, including the material prop-

erties of the plate. When setting your own transient analysis, make sure that you choose time settings

appropriate to the physics you are solving.

1. In the Mechanical application’s Outline view, select Project > Model > Transient > Analysis Settings.

The details of Analysis Settings appear in the Details of “Analysis Settings” below the Outline

view.

2. In the Details of “Analysis Settings”, specify the following settings under Step Controls (do not type

units next to the time values):

1. Set Step End Time to 10.

2. Set Auto Time Stepping to Off.

3. Set Define by to Substeps.

4. Set the Number of Substeps to 1.

Inserting Loads

The loads applied for the structural analysis are equivalent to the boundary conditions in a fluid analysis.

In this section, you will set the following loads and interface:

• a fixed support on the bottom of the plate

• a fluid-solid interface where the plate interacts with the fluid

• a pressure load on one side of the plate, to start the oscillation

On the surfaces of the plate that lie coincident with the symmetry planes, you will not set a load. With

no load set, the default of an unconstrained condition will be applied on these two surfaces. For this

particular case, this unconstrained condition is a reasonable approximation of the frictionless support

that would otherwise be applied.

Defining the Fixed Support

The fixed support is needed to hold the bottom of the thin plate in place. Set up the fixed support:

1. Right-click Transient in the Outline view, and select Insert > Fixed Support from the shortcut menu.




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2. Rotate the geometry using the Rotate button so that the bottom (low-y) face of the solid is visible,

then select Face and click the low-y face.

That face is highlighted to indicate the selection.

3. In the Details of “Fixed Support” view, click Apply beside Geometry to set the fixed support.

If the Apply button is not visible, select Fixed Support in the Outline view and, in the Details

view, click the text next to the Geometry setting to make the Apply button reappear.

The text next to the Geometry setting changes to 1 Face.

Defining the Fluid-Solid Interface

The fluid-solid interface defines the interface between the fluid in the Fluid system and the solid in the

Structural system. Data will be exchanged across this interface during the execution of the simulation.

When setting up your structural system for a coupled analysis, you need to define this interface on regions

in the structural model that will receive force data from the Fluid system.

1. In the Outline view, right-click Transient and select Insert > Fluid Solid Interface from the shortcut

menu.

2. Using the same face-selection procedure described earlier in Defining the Fixed Support (p. 88), select

the three faces of the geometry that form the interface between the structural model and the fluid

model (low-x, high-y and high-x faces). Hold down Ctrl to be able to select multiple faces.

3. In the Details of “Fluid Solid Interface”, beside Geometry, click Apply.

The text next to the Geometry setting changes to 3 Faces.

Note that this load (fluid-solid interface) is automatically given an Interface Number of 1.

Defining the Pressure Load

The pressure load on one side of the plate provides the initial pressure of 100 Pa for the first 0.5 s of

the simulation. This pressure to the plate starts the oscillation. It is defined using tabular data.

1. In the Outline view, right-click Transient in the tree view and select Insert > Pressure from the shortcut

menu.

2. In the Viewer, select the low-x face. In the Details of “Pressure” view beside Geometry, click Apply.

The text next to the Geometry setting changes to 1 Face.

3. In the Details of “Pressure” view, click the cell next to Magnitude, and using the arrow that appears,

select Tabular.

The Tabular Data view appears on the bottom right of the Mechanical application window. The

times of 0 s and 10 s are the beginning and end of your analysis, based on the time duration (10

s) that you specified earlier.

4. In Tabular Data, set a pressure of 100 Pa in the table row corresponding to a time of 0. Do not type inunits.



Defining the Physics in the Mechanical Application


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5. You now need to add two new rows to the table. Do this by typing the new time and pressure data into

the empty row at the bottom of the table. Notice that the rows are automatically re-ordered based on

the time value. Add the data from Table 4: Tabular Data for Step Pressure Load (p. 90).

Table 4: Tabular Data for Step Pressure Load

Pressure (Pa)Time (s)

1000

1000.5

00.51

010

You now have tabular data similar to a step function for your pressure, with 100 Pa applied for 0.5

s. The step function is displayed in the graph to the left of the table.

6. The settings for the structural physics are now complete. Save these settings by selecting File > Save

Project from Mechanical’s main menu.

7. If you do not intend to execute a command line run using the set up from the Mechanical system, proceed

to Completing the Setup for the Structural System (p. 91). If you do intend to execute a command line

run, continue with the next section.

Preparing for a Command-Line Run of the Structural System

If you intend to execute a command-line run using the set up from the structural system:

1. From the Mechanical application, select Tools > Write Input File.

2. Specify the path and APDL Input File (SystemCouplingOscillatingPlate_CmdLine\structur-al.dat) that you will use later.

Tip

The Write Input File option is available only if you have Transient (A5) selected in the

Outline tree.

Note

Though out of the scope of this tutorial, below is information about augmenting your

structural setup, and transferring the structural setup from the Mechanical application to the

Mechanical APDL application.

• In some cases, you may need to augment your structural setup in the Mechanical APDL application.

If this is the case, then open that application and select File > Read Input From to choose the

.dat file created by Mechanical. Once the .dat file has been read, make your setup modifications

and write a Mechanical APDL Database file using File>Save As Jobname.db or File >Save As.

Starting the Mechanical APDL solver from the created database file is explained later in the tu-

torial.




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• Transferring the structural setup from the Mechanical application to the Mechanical APDL applic-

ation is facilitated in ANSYS Workbench.To do this, right-click the Mechanical system's Setup

cell (A5), and select Transfer to New > Mechanical APDL. Once the new Mechanical APDL

system is introduced, update the upstream Mechanical system's Setup cell (A5).The setup will

be read into the Mechanical APDL user interface by right-clicking that system's Analysis cell andselecting Edit in Mechanical APDL.

Completing the Setup for the Structural System

On the Project Schematic, the Structural system’s Setup cell (A5) appears in an update-required state.

To complete the setup in the Structural system, you need to ensure that all the data is in the right state

in the Project Schematic.

1. In the Structural system, right-click the Setup cell (A5) and select Update from the shortcut menu.

The status of the Setup cell changes to up-to-date. All cells in the Structural system down to theSetup cell should now appear in an up-to-date state.

2. From the main menu, select File > Save to save the project.

The set up for the Structural system is complete. Remember that you will not solve the structural ana-

lysis from the Mechanical application because you are using the System Coupling system to solve both

Structural and Fluid systems at the same time. In the next section, you will set up the Fluid system.


You will use the Fluent application to set up your Fluid system, but first you need to generate the mesh

using the Meshing application. The fluid Geometry cell (B2) is up-to-date because it shares the geometry

with the structural analysis, and so you start your Fluid system’s setup with creating a mesh.

Generating the Mesh for the Fluid System

You will generate a mesh for the Fluid system using the Meshing application. For this geometry, you

will use a swept mesh across the x-y plane, creating a hex mesh with a depth of one element.

1. In the Project Schematic, double-click the Fluid system’s Mesh cell (B3) to open the Meshing application.

The Meshing application appears in a separate window.

2. In the Meshing application’s Outline view on the left, expand Geometry to see the two geometries, solidand Part.

3. For the fluid analysis, you need to generate the mesh for only the fluid bodies.To do this, you need to

first suppress the structural body.

Right-click solid and select Suppress Body

The solid body is now suppressed and its status changes to an x mark. You now will only see the

fluid bodies in the Graphics view.

4. In the Outline on the left, click Mesh. In the Details of “Mesh” below, under Defaults, notice that the

Physics Preference is set to CFD and Solver Preference is set to Fluent.





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5. Now you need to define sweep as the meshing method, and set up all of the information that the sweep

method needs:

a. In the Outline, right-click Mesh and select Insert > Method.

Automatic Method will appear under Mesh

b. Click Body , and then select all five fluid bodies in the Graphics view. Use the Ctrl key to select

multiple bodies. Note that the fifth fluid body is very thin, and is above the plate.

c. With all five bodies selected, in the Details of “Automatic Method” – Method, beside Geometry

click No Selection. Click the Apply button that appears.

The text next to Geometry changes to 5 Bodies.

d. Under Definition, set Method to Sweep.

Notice that in the Outline above, under Mesh, the method is now renamed to Sweep Method.

e. In the Details of “Sweep Method” – Method, next to Src/Trg Selection, click Automatic. Using the

arrow that appears, select Manual Source.

Manual Source enables you to dictate which surfaces are used as the source for the sweep

meshing. Source is highlighted, indicating that information about which surfaces to use is

needed.

f. Select Face , then Ctrl-select all five fluid faces on one of the walls in the x-y-plane (either side of

the wall will work).

g. In the Details view, beside Source, click No Selection. Click the Apply button that appears.

The text next to Source changes to 5 Faces.




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h. Set Free Face Mesh Type to All Quad so that all of the mesh elements are quadrilateral.

i. Next to Sweep Num Divs, set the value to 1.

j. In the Outline above, click Mesh. In the Details of “Mesh”, expand Sizing and set Min Size to 0.06

and Max Face Size to 0.2. These settings control the size of the mesh elements that will be generated.

6. Now that all of the settings for your swept mesh are complete, you need to generate the mesh. In the

Outline, right-click Mesh and select Update.

The swept mesh that you have defined is now generated for your fluid bodies.

7. Select File > Save Project, and then File > Close Meshing to close the Meshing application.





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Defining the Physics in the ANSYS Fluent Application

In the Fluent application, you are setting up the fluid analysis, and defining the coupling interface. You

will not solve the fluid analysis from the Fluent application because you are using the System Coupling

system to solve both structural and fluid systems at the same time.

When setting up your own two-way coupled analysis, it is a best practice to set up and solve the fluid

analysis before continuing with your coupled analysis. If issues occur within your fluid system, the isolated

analysis is easier to troubleshoot than the more complex coupled analysis.

This section describes the step-by-step definition of the fluid physics:

Adding the Solution Setup Settings

Defining the Dynamic Mesh

Adding the Solution Settings

Preparing for a Command-Line Run of the Fluent System

Adding the Solution Setup SettingsYou now need to open your analysis in the Fluent application, set the Fluid analysis to be transient,

and add material to the fluid geometry.

1. In the Project Schematic, double-click the Fluid system’s Setup cell (B4) to open the Fluent application.

2. The Fluent Launcher opens in a new window. Under Options, select Double Precision.

3. Use the remaining default options (3D and serial), and click OK to close the Fluent Launcher.

The Fluent application opens in a new window, and the mesh file is automatically loaded.

4. On the left, select Setup > General. Under Time, click the Transient option.

5. On the left, select Setup > Materials > Air to assign material to your geometry. Click the Create/Edit

button, and in the dialog box that appears, for Density (kg/m3) type 1 and Viscosity (kg/m-s) type 0.2.

Do not type units.

Click Change/Create to save these changes, and then click Close.

6. Under Setup > Models, note that by default, the viscous model is laminar and the energy model is turned

off. No changes are needed to these settings.

Defining the Dynamic Mesh

A dynamic mesh is needed for any coupled analysis where a system receives displacements. In this tu-

torial, the plate is oscillating back and forth, and the dynamic meshing settings determine how the

mesh of the fluid bodies react to this deformation of the moving structural body.

The mesh on the fluid-structural interface is static, so as the fluid mesh is modified to accommodate

the deformation in the transient system, the mapping on this coupling interface stays consistent.

Set up the dynamic mesh:

1. On the left, select Setup > Dynamic Mesh.

2. Check the Dynamic Mesh option in the panel.The settings for Dynamic Mesh are now available.




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3. Under Mesh Methods, Smoothing is checked by default. Click the Settings button to specify the settings

for the smoothing used.

The Mesh Method Settings dialog box appears.

a. On the Smoothing tab, set Method to Diffusion.

b. For the Diffusion Parameter, type 2. Click OK to close the dialog box.

4. Under Dynamic Mesh Zones, click Create/Edit to specify which zones in your geometry will have dynamic

meshing.

The Dynamic Mesh Zones dialog box appears.

5. Define the dynamic mesh settings needed for the surface “symmetry1”, which is the wall in the x-y plane

that goes through the origin. This surface will be affected by the solid body’s displacement, and its mesh

needs to be able to deform.

a. In the Dynamic Mesh Zones dialog box, under the Zone Names drop down list, select the zone

“symmetry1”.

b. Set its Type as Deforming.

c. Select the Geometry Definition tab.

d. Specify the Definition as “plane”.

e. Specify Point on Plane as 0,0,0

f. Specify Plane Normal as 0,0,1

g. Click Create at bottom of dialog box to create this dynamic mesh zone.

The list of Dynamic Mesh Zones on the right side of the dialog box now includes the “sym-

metry1”.

6. Define the dynamic mesh settings needed for the surface “symmetry2”, which is the second wall in the

x-y plane. This surface will be affected by the solid body’s displacement, and its mesh needs to be able

to deform.

a. Under the Zone Names drop down list, select the zone “symmetry2”.

b. Set its Type as Deforming.

c. Select the Geometry Definition tab.

d. Specify the Definition as “plane”.

e. Specify Point on Plane as 0,0,0.4

f. Specify Plane Normal as 0,0,1

g. Click Create at bottom of dialog box to create this dynamic mesh zone.

The list of Dynamic Mesh Zones now includes the “symmetry2”.





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7. Define the dynamic mesh settings needed for the surface “wall_bottom”, which is the two surfaces on

the bottom of the fluid zones (the two surfaces are interrupted by the solid body in the middle of the

geometry). This surface is not affected by the solid body’s displacement, and so its mesh should remain

stationary.

a. Under the Zone Names drop down list, select the zone “wall_bottom”.

b. Set its Type as Stationary, then click Create at bottom of dialog box to create this dynamic mesh

zone.

The list of Dynamic Mesh Zones now includes the “wall_bottom”.

8. Repeat the previous step's instructions to create stationary dynamic mesh zones for the three surfaces

below.These three surface complete the enclosed cavity, and they are not affected by the solid body’s

displacement.Their mesh should remain stationary.

• “wall_top”

• “wall_side1”

• “wall_side2”

9. Define the dynamic mesh settings needed for the surfaces in the zone “wall_deforming”, which are the

surfaces surrounding the solid body.These surface will deform throughout the simulation.

a. Under the Zone Names drop down list, select the zone “wall_deforming”.

b. Set its Type as System Coupling, then click Create at bottom of dialog box to create this dynamic

mesh zone.

The list of Dynamic Mesh Zones now includes the “wall_deforming”.

10. You now have seven dynamic mesh zones defined and listed on the right of the dialog box. Click Close.

Adding the Solution Settings

Set the solutions settings in the Fluent application so that your fluid system is ready to be solved:

1. On the left side of the Fluent application, select Solution > Solution Methods.

a. Under Pressure-Velocity Coupling > Scheme, select Coupled.

b. Under Spatial Discretization > Momentum, ensure Second Order Upwind is selected.

2. On the left side of the Fluent application, select Solution > Calculation Activities, then specify Autosave

Every (Time Steps) to be 2.

3. On the left side of the Fluent application, select Solution > Run Calculation, then:

a. Specify Number of Time Steps to be 10. Note that the system coupling’s number of time steps will

override this value.




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b. Specify the Max Iterations/Time Step to be 5.This value is the maximum amount of times that

Fluent can iterate within a coupling iteration.

c. Leave the default Time Step Size (s) as 1, but note that the system coupling’s time step size will

override this value.

4. On the left side of the Fluent application, select Solution > Solution Initialization. Under Initialization

Methods, ensure the Standard Initialization option is selected.

5. In Solution > Solution Initialization, click Initialize.

6. Save the project.

7. If you intend to execute a command line run using the setup from the Fluent system, go to Preparing for

a Command-Line Run of the Fluent System (p. 97).

8. If you do not intend to execute a command line run using the setup from the Fluent system, Select File

> Close Fluent to close Fluent and to return to the Project Schematic.

The setup for the Fluid system is complete. Remember that you will not solve the fluid analysis

from the Fluent application because you are using the System Coupling system to solve both

structural and fluid systems at the same time. In the next section, you will set up the System

Coupling system.

Proceed to the section Defining and Running the Coupling in the System Coupling Applica-

tion (p. 97).

Preparing for a Command-Line Run of the Fluent System

If you intend to execute a command line run using the set up from the Fluent system, select File >

Export > Case from the main menu in the Fluent user interface, and specify the path and Case File

(SystemCouplingOscillatingPlate_CmdLine\fluidFlow.cas) that you will use later.

Important

You should perform this step before updating the coupled solution within the Workbench

environment for the following reasons:

• Editing the Fluent system’s Setup cell after a solution is executed will clear all existing solution

files.

• Editing the Fluent system’s Solution cell after a solution is executed will load the most recent

(rather than the original) case and data files.

You may now close Fluent.


In the System Coupling system, you are setting up the coupling between your Structural and Fluid

analyses. You will use the System Coupling system to solve both of these analyses at the same time.

Notice that in the Structural and Fluid systems, all of the cells up to Setup are marked as up-to-date.





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To set up the transient analysis settings for your coupled analysis:

1. In the Project Schematic, double-click the System Coupling system’s Setup cell (C2).

In the dialog box, click Yes to allow upstream data to be read. The System Coupling system is ob-

taining data from the Structural and Fluid systems’ Setup cells (A5 and B4).

The System Coupling application opens in a new tab in your Workbench project.

2. In Outline of Schematic C1: System Coupling, select System Coupling > Setup > Analysis Settings.

3. In Properties of Analysis Settings (on the bottom left):

a. Set Duration Controls > End Time to 10.

The end time is the same as the Structural system’s time duration. The choice of 10 s givesenough time to observe the plate oscillating a few times. System Coupling’s end time value

always overrides the number of time steps specified in the Fluent application.

b. Set Step Controls > Step Size to 0.1.

The coupling iteration size is same as the transient analysis’ time step, and the choice of 0.1

s is small enough for use to observe the plate’s oscillations to a reasonable degree. System

Coupling’s step size value always overrides the time steps size specified in the Fluent applica-

tion.

c. Ensure the Maximum Iterations is set to 5.

For this system to converge, 5 coupling iterations within each coupling step is sufficient. If

your own system has trouble converging within the coupling step, you may want to increase

the number of maximum iterations or reduce the time step size.

Creating the Data Transfers

For your two-way coupled analysis, data from the Structural and Fluid solutions need to be shared

throughout the solution process. System Coupling coordinates the transfer of data between these two

systems using the Data Transfers that you create.

1. In Outline of Schematic C1: System Coupling, expand System Coupling > Setup > Participants untilall region components are visible.

2. Ctrl-select the "wall_deforming" (from the Fluid system) and "Fluid Solid Interface" regions (from the

Structural system). With both selected, right-click on one of those regions and select Create Data

Transfer.

Under System Coupling > Setup > Data Transfers, Data Transfer and Data Transfer 2 are created:

a. Data Transfer:here, the surface of the Structural system around the plate transfers displacement to

the surface of the Fluid system around the plate.

b. Data Transfer 2: here, the surface of the Fluid system around the plate transfers force to the surface

of the Structural system around the plate.




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Click on System Coupling > Setup>Data Transfers > Data Transfer. In the Properties of Data-

Transfer on the bottom left, notice that the source, target and variable transferred are already

defined for each of these data transfers. These settings are also already defined for Data Transfer

2.

Preparing System Coupling for Restarts

You should ensure that System Coupling is producing restart data, in the event that the System Coupling

analysis needs to be restarted.

1. Under System Coupling > Setup > Execution Control, select Intermediate Restart Data Output.The

restart output frequency for the system coupling analysis is defined and controlled by these settings.

2. In Properties of Intermediate Restart Data Output:

• Set Output Frequency to At Step Interval.

• Set Step Interval to 5.

3. Select File > Save to save your settings before solving.

Note

Recall that earlier, the Fluent auto-save frequency was set to 2 so that Fluent will output

result files (case and data files) every two time steps (that is, 2, 4, 6, 8, 10, etc.). Fluent

will also output additional result files at 5, 10, 15, 20 etc. based on the Step Interval

frequency specified for the Intermediate Restart Data Output. In CFD-Post, both sets

of files will be available for post-processing.

Solving and Restarting the Coupled Analysis

During the solution process, the System Coupling system coordinates the solving of your Structural and

Fluid systems as well as the data transfers between these two systems. The Fluid system solves using

the Structural solution’s displacement data, and the Structural system solves using the Fluid solution’s

force data.

1. To start solving the coupled analysis, in Outline of Schematic C1: System Coupling, right-click Solution

and select Update.

The solution progress begins, and progress is summarized in the System Coupling Chart andSolution Information views, as well as the Workbench schematic progress view. This solution will

run for 100 coupling steps because you specified an end time of 10 s in System Coupling (“time

duration” in Mechanical), and each coupling step represents 0.1 s (“step size” in System Coupling,

and “time step” in Mechanical).

Note that you can alternatively start solving the coupled analysis from Workbench’s Project

Schematic:

a. To return to the Project Schematic, click on the Project tab in Workbench.To start the solution

process from the Project Schematic view, right-click the System Coupling system’s Solution cell

(C3) and choose Update.





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Notice that the Structural and Fluid systems’ Solution cells’ (A6 and B5) update operations

are disabled because the coupled solution process must be run through the System Coupling

system.

b. Click on the System Coupling tab to return to the System Coupling system and observe the coupled

solution progress.

If you closed the System Coupling application and so there is no System Coupling tab, you

can re-open the System Coupling user interface by double-clicking on its Solution cell (C3).

2. On the bottom right of the screen, click on Show Progress to see the progress of your solution.

3. As your analysis is solved, in the Solution Information view, information from the System Coupling Log

file is displayed. Useful information includes:

a. Each coupling step and coupling iteration is recorded with information about convergence of the

data transfer.

b. At the beginning of the file (scroll up in your Solution Information view), there is an overview of

the participants (the Fluid and Structural system), the data transfers, the System Coupling settings,

and a mapping summary.

c. The Mapping Summary has information about the percentage of nodes on your fluid-structure inter-

face that are mapped. This information is used to determine the quality of the mapping in your system.

4. Restart data will be output during the solution process. An additional note will be seen in the System

Coupling log output under Solution Information indicating the name and frequency of the system

coupling result file. For example, the intermediate result file is written: scResult_01_000005.scr.The restart

data for Fluent will also be output at the same frequency during the coupled solution. When the coupled

solution completes, Mechanical restart files (that is, file.r001, file.r002 etc.) will be visible in the Workbench

project files (that is, they are automatically transferred from the solver temporary/scratch folder). The file

naming convention is such that file.r001 refers to a Mechanical restart file at step 5, file.r002 refers to a

Mechanical restart file at step 10, and so on.

5. The System Coupling solution is complete when the System Information view reads “System coupling

run completed successfully.”

6. Select File > Save to save the project, and then click on the Project tab to return to the Project Schem-

atic.

Preparing for a Command-Line Run of the System Coupling System

If you intend to execute a command-line run using the setup from the System Coupling system, you

need to export the System Coupling Input (SCI) file. To do this:

1. In your Project Schematic, make sure that the System Coupling Setup cell (C2) is in an up-to-date state.

2. If your System Coupling tab is not open, double-click System Coupling’s Setup cell (C2).

3. From the System Coupling tab, in the main menu, select File > Export SCI File.

4. Specify the path and SCI file (SystemCouplingOscillatingPlate_CmdLine\coupling.sci)

that you will use later.




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5. Select File > Save to save the project, and then click on the Project tab to return to the Project Schem-

atic.


You will use CFD-Post to view the results of your coupled analysis. You have simulated the plate oscil-

lating in a closed cavity filled with air. The results you have obtained show the plate and surrounding

air for a few oscillations, and you will be able to use CFD-Post to see the motion of the plate as it is

damped.

In Workbench, you need to set up the Project Schematic so that CFD-Post can read the solution of

your Structural and Fluid systems.

To view the results in CFD-Post:

1. In the Project Schematic, drag the Structural Solution cell (A6) to the Fluid Results cell (B6).

2. Double-click the Fluent Results cell (B6) in the Fluid system to launch CFD-Post.

CFD-Post opens in a new window. Both sets of results are loaded into the CFD-Post session, and

are ready for you to view.

Creating an Animation

An animation is a good way to view results in a transient analysis. In this animation, you will show:

• The pressure and velocity of the fluid on the symmetry plane

• The deformation of the plate geometry, with stress visible

Set up your animation:

1. From the task bar at the top of the CFD-Post application, select Tools > Timestep Selector to open the

Timestep Selector dialog box.

The Timestep Selector dialog box shows the results time history for both Fluent and MAPDL system

coupling.

2. In the Timestep Selector dialog box, on the Fluid tab, select a Time of 0.2 s for the Fluid case, then click

Apply.

Close the Timestep Selector dialog box.

3. Under Cases > Fluid at 0.2s > Part Fluid, check the “symmetry1” zone under the Fluid case to display

that zone, then double-click to edit it.

a. In Details of symmetry1, on the Color tab set the Mode to Variable and set Variable to Pressure.

b. On the Render tab, clear the Lighting check box and check Show Mesh Lines.

c. Click Apply to save your changes.The pressure at 0.2 s is now visible on the one side of the fluid

geometry.





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4. Under Cases > Structural at 0.2s > Default Domain, check the Default Boundary zone, then double-

click to edit it.

a. In the Details of Default Boundary, on the Color tab, set the Mode to Variable and set Variable

to Von Mises Stress.

b. On the Render tab enable Show Mesh Lines.

c. Click Apply. Stress is now visible on the structural body.

5. From the task bar at the top of the CFD-Post application, select Insert > Vector to create a vector plot.

Accept the default name and click OK.

a. In the Details view on the Geometry tab, set the Locations to symmetry1, set Sampling to Face

Center, and ensure that Variable is set to Velocity.

b. On the Symbol tab, set Symbol to Arrowhead3D.

c. Click Apply. A vector plot of the velocity is now visible on the one side of the fluid geometry.

6. In the Outline under User Locations and Plots, clear the Default Legend View 1 check box.

7. From the task bar at the top of the CFD-Post application, select Insert > Text and click OK to accept the

default name.

a. In the Details of Text 1 view, for Text String, type Time = . Check the Embed Auto Annotation,

and from the Expression drop-down list select Time.

b. On the Location tab, set X Justification and Y Justification to None, and set the Position text as0.1 in the first field, and 0.2 in the second field.

c. Click Apply.

The corresponding transient results are loaded into the Animation in CFD-Post, and when you run the

animation, you can see the mesh move in both the Fluent and Mechanical regions.

1. Zoom in so that you can see the oscillating plate clearly.

2. At the top of the CFD-Post application, click Animation .

The Animation dialog box appears.

3. Select Keyframe Animation.

4. In the Animation dialog box:

a. Click New to create KeyframeNo1.

b. Highlight KeyframeNo1, then change # of Frames to 48.




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c. Load the last timestep (100) using the Timestep Selector (found at the top of the CFD-Post Inter-

face).

d. Back in the Animation dialog box, click New to create KeyframeNo2.

The # of Frames parameter has no effect for the last keyframe, so leave it at the default value.

e. Click the More Animation Options button , then check the Save Movie check box.

f. Click Browse next to Save Movie to set a path and file name for the movie file.

If the file path is not given, the file will be saved in the directory from which CFD-Post was

launched.

g. Click Save.

The movie file name (including path) will be set, but the movie will not be created yet.

h. If frame 1 is not loaded (shown in the F: text box in the middle of the Animation dialog box), click

To Beginning to load it.

Wait for CFD-Post to finish loading the objects for this frame before proceeding.

i. Click Play the animation .

The movie will be created as the animation proceeds. This process will be slow, since a timestep

must be loaded and objects must be created for each frame.

j. Save the results by selecting File > Save Project from the main menu.

k. Close the animation dialog box. Your animation is now saved in the file path you specified.You can

play the video in any media player.

Plotting Results on the Solid

You will use a chart to display the deformation of the solid body. One point at the top of the plate is

used to track the displacement in the chart. This chart is a useful way to view the damping that occurs

in the plate’s motion due to the interaction with the fluid.

1. Create a point in the solid domain by using node number 77.This point is at the top corner of the solid

body, and will be used to track the deformation of the plate.

a. From the task bar at the top of the CFD-Post application, select Insert > Location > Point. Click OK

to accept the default name.

b. In the Details view, on the Geometry tab, set Domains to Default Domain, set Method to Node

Number, and set Node Number to 77.

c. Click Apply. On your model, cross hairs appear on node number 77, so you can see where this point

is on your solid body.





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2. To view the deformation using the point you just created, insert an XY Transient Chart for the data at this

node (“Point 1”). In the chart you create, the x-axis is time, and the y-axis is the total mesh displacement.

a. From the task bar at the top of the CFD-Post application, select Insert > Chart; click OK to accept

the default name.

b. In the Details view, on the General tab, set Type to XY - Transient or Sequence

c. On the Data Series tab, for Name type System Coupling, and set Location to Point 1.

d. On the X Axis tab, ensure that the Expression is Time.

e. On the Y Axis tab, set the Variable to Total Mesh Displacement X.

3. Click Apply to generate the chart of mesh displacement over time.

After the chart is generated, note the damping that is visible in the plate’s motion. The plate does

not return to equilibrium in this chart because of the length of time we chose for the simulationof this case. To see the full damping of the system, you would need to simulate the case for a

longer time duration.

4. Save the project and then select File > Close CFD-Post.

Post-Processing in Mechanical

You can also see the structural results of your FSI analysis in the Mechanical application. Note that the

Mechanical system does not have any information about results on the fluid bodies.

1. From the Project Schematic, double-click the Results cell (A7) to relaunch ANSYS Mechanical.

The Mechanical application opens in a new window.

2. In the Outline view, right-click Solution A6 and select Insert > Stress > Equivalent (von Mises) results.

3. Right-click Solution A6 again and select Insert > Deformation > Directional results.

4. Right-click Solution A6 again and select Evaluate All Results.

The equivalent stress and directional deformation of the place are now visible on your model.

5. Under Solution A6 click Equivalent Stress to view the stress on the structural body.

6. Under Solution A6 click Directional Deformation to view the deformation of the structural body.

7. From your Project Schematic, save the project.

All systems are now complete and the Project Schematic is up-to-date.

Setting Up and Executing a Coupled Analysis Restart from Workbench

1. In the Mechanical application,

a. Under Project > Model > Transient, select Analysis Settings.

b. In Analysis Settings Details, set Restart Type to Manual.




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c. In Analysis Settings Details, set Current Restart Point to Load Step 50, Substep 1 (that is, 5s).

d. Close ANSYS Mechanical.

2. From the Project Schematic, double-click the Fluid Solution cell (B5):

a. From the File menu, select Solution Files....

b. In the Solutions Files dialog box that appears, click on 100 time steps, 10s - Current to deselect it,

and then click on 50 time steps, 5s to select this time step.

c. Select the Read button. Fluent will read in the case/data file associated with 5s.

d. Close Fluent.

3. From the Project Schematic, double-click the System Coupling Setup cell (C2):

a. From the outline, select Setup > Analysis Settings.

b. In Properties of Analysis Settings, under Initialization Controls, from the Coupling Initialization

drop-down list, select Step 50,Time 5[s].

c. Optional: Under Execution Control > Intermediate Restart Data Output, set Output Frequency to

None. If this is not done, there will be a second set of restart files output under the Workbench project.

4. To start solving the coupled analysis restart, right-click the Solution branch in Outline of Schematic C1:

System Coupling, and select Update. A summary of the solution progress in the System Coupling Chart

(starting from 5s) and Solution Information views (also starting from 5s), as well as the Workbench

Schematic Progress view.

5. Once your solution is complete, select File > Save to save your project.

6. You have now used the Workbench, Fluent, Mechanical, and System Coupling interfaces to complete this

tutorial’s simulation. If you would like to complete the optional steps to run this tutorial using the command

line, continue with Executing the Coupled Analysis from the Command Line (p. 105).

Otherwise, you are now finished Oscillating Plate with Two-Way Fluid-Structure Interaction tutorial.

When you are finished viewing your results, and select File > Save from the main menu, and then

File > Exit to close your Workbench project.


This section describes how to execute the analysis for this tutorial from the command line. In this example,all executables are run in batch mode (there are no user interfaces or launchers) from a standard install-

ation on a single Windows 64-bit machine.

Note

In order to be able to execute runs from the command line, all executables and dynamic

library dependencies must be properly resolved. For more information, see Executing System

Couplings Using the Command Line.





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Preparing the Required Input Files

Runs executed from the command line require input files for each of the executables used in the coupled

analysis.

1. If you have not been creating the input files for the command-line analysis as you worked through thetutorial, then follow the instructions in Optional: Preparing for a Command-line Run (p. 82) to create the

file structure for the command-line run.

2. If you have not been creating the input files for the command-line analysis as you worked through the

tutorial, then follow directions in the sections referenced below and create the listed input files in theSystemCouplingOscillatingPlate_CmdLine directory:

a. Create the file structural.dat according to Preparing for a Command-Line Run of the Structural

System (p. 90).

b. Create the file fluidFlow.cas according to Preparing for a Command-Line Run of the Fluent

System (p. 97).

c. Create the file coupling.sci according to Preparing for a Command-Line Run of the System

Coupling System (p. 100).

3. An additional input file is required to execute the Fluent solver in batch mode. In the SystemCouplin-

gOscillatingPlate_CmdLine directory, create a journal file named fluidFlow.jou that contains

the following:

file/start-transcript "Solution 1.trn"

file set-batch-options , yes ,

file/read-case/fluidFlow.cas

s i i(sc-solve)

wcd FLUENTRestart.cas.gz

exit

ok

Running the Analysis

To run the analysis:

1. Open a command window, and from theSystemCouplingOscillatingPlate_CmdLine\Coup-

ling_CmdLine subdirectory, run System Coupling service using the following command:

"C:\Program Files\ANSYS Inc\v160\aisol\bin\winx64\Ansys.Services.SystemCoupling.exe"–inputFile ..\coupling.sci

Tip

You may prefer to add the previous command to a batch file.

Now when you run the System Coupling service command, the coupling service starts and creates

the System Coupling Server File (SystemCouplingOscillatingPlate_CmdLine\Coup-

ling_CmdLine\scServer.scs). For details, see Files Generated by Coupling Service (p. 56).

2. Open scServer.scs and review its contents, which will be similar to the following:




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12345@yourmachine

2

Solution

Structural

Solution 1

Fluid

where:

• 12345 is the server port

• yourmachine is the host's name

• 2 indicates that two participant connections are expected

• The unique names to be used when starting the structural and fluid flow solvers are, respectively:

"Solution" and "Solution 1". The unique names from the solver(s) are encoded in the coupling service

input file and are reported here along with the names of the systems in the Workbench schematic.

Note this correlation, since the unique names are needed when starting the respective solvers. Note,

as well, that the unique names are determined by Workbench and can vary depending upon the orderin which systems were introduced into the schematic.

3. Copy the fluidFlow.cas file into the FluidFlow_CmdLine subdirectory.

This step ensures that Fluent treats that subdirectory as the run directory, and generates all sub-

sequent case and data files there. By keeping the basic input files separate from the run directories,

you can easily clear or delete the run directories for retries.

4. From a new command window, change to the FluidFlow_CmdLine subdirectory, then run the Fluent

solver by entering the following command:

"C:\Program Files\ANSYS Inc\v160\fluent\ntbin\win64\fluent.exe" 3ddp -hidden

-driver null -scport=12345 -schost=yourmachine -scname="Solution 1"

-i ..\fluidFlow.jou>FLUENT.out

5. From a new command window, change to the Structural_CmdLine subdirectory, then run the

Mechanical APDL solver by entering the following command:

"C:\Program Files\ANSYS Inc\v160\ansys\bin\winx64\ANSYS160.exe" -b -scport 12345

-schost yourmachine -scname "Solution" -i ..\structural.dat -o ANSYS.out

Note

• In steps 4 and 5 above, you may need to adjust the coupling service port and host (12345and yourmachine, respectively) and solvers' unique names ("Solution" and "Solution 1"

for the Mechanical APDL and Fluent solvers, respectively) based upon information extracted

from the system coupling server file.

• The input file name,structural.dat, will need to be replaced with the name of the

manually-created input file (e.g. mapdl.dat) if such a file was created to enable a resume

from a Mechanical APDL database file.





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Restart Analysis Execution

For the sake of simplicity, the restart analysis uses the same solver and coupling service directories in

which the initial analysis was performed.

Preparing the Required Input Files

In the SystemCouplingOscillatingPlate_CmdLine directory, create the following:

1. Create a restart journal file for the Fluent solver. Name this file fluidFlowRestart.jou, and have it

contain the following:

file/start-transcript "Solution 2.trn"

file set-batch-options , yes ,

rcd/fluidFlow-1-00050.cas

(sc-solve)

exit

ok

Note

The "-1-" in the file name fluidFlow-1-00050.cas represents the run number and

may be different in your system, depending upon how many runs were completed before

writing the .cas file.

2. Create a restart input file for the Mechanical APDL solver. Name this file structuralRestart.dat,

and have it contain the following:

/batch

/solu/gst,on,on

antype,4,rest,50,1,continue

solve

save

finish

/exit

Run the Analysis

Much as when you ran the initial analysis:

1. Open a command window, change to the Coupling_CmdLine subdirectory, and run the System

Coupling service using the following command:"C:\Program Files\ANSYS Inc\v160\aisol\bin\winx64\Ansys.Services.SystemCoupling.exe"

–inputFile ..\coupling.sci –resultFile scResult_01_000050.scr

2. Open the system coupling server file (scServer.scs) and note the coupling server’s port and host.

Note that the solvers’ unique names have not changed because they are encoded in the coupling service’s

input file.

3. Change to the FluidFlow_CmdLine subdirectory, and run the Fluent solver by entering the following

command:

"C:\Program Files\ANSYS Inc\v160\fluent\ntbin\win64\fluent.exe" 3ddp

-hidden -driver null -scport=12345 -schost=yourmachine -scname="Solution 1"-i ..\fluidFlowRestart.jou>FLUENTRestart.out




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4. Change to the Structural_CmdLine subdirectory, and run the Mechanical APDL solver by entering

the following command:

"C:\Program Files\ANSYS Inc\v160\ansys\bin\winx64\ANSYS160.exe" -b

-scport 12345 -schost yourmachine -scname "Solution"

-i ..\structuralRestart.dat -o ANSYSRestart.out

Note

In steps 3 and 4 listed above, you may need to adjust the coupling service port and

host (12345 and yourmachine, respectively) and solvers' unique names ("Solution"

and "Solution 1" for the Mechanical APDL and Fluent solvers, respectively) based upon

information extracted from the system coupling server file.

Loading the Results into CFD-Post

To load the Results files into CFD-Post:

1. To start CFD-Post, from the Start menu, go to Start > All Programs > ANSYS 16.0 > Fluid Dynamics >

CFD-Post 16.0.

2. From CFD-Post, select File > Load Results.

3. Open the final CAS file, which will have a name similar to FluidFlow_CmdLine\fluidFlow-1-

00100.cas.

4. Again select File > Load Results.

5. In the dialog box that appears, select Keep current cases loaded, and clear Open in new view.

6. Open the file Structural_CmdLine\file.rst. When post-processing results, your structural results

are named after the name of the file they are loaded from. From this command line run, your structural

results will appear under the name “file” (because of file.rst).

7. Proceed to Viewing Results in CFD-Post (p. 101) for instructions on how to post-process the results. When

following these instructions, remember that your command line structural results will appear under the

name ”file”, and not “Structural”.





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