Upfront CFD Buyers Guide

Upfront CFD Buyer’s Guide

Published By: Blue Ridge Numerics, Inc.Copyright © 2010, All rights reserved.

Page 2 | www.c fdes ign .com Upfront CFD Buyer’s Guide

Copyright © 2010 Blue Ridge Numerics, Inc. All rights reserved.

The emergence of DigiTal flow anD Thermal ProToTyPing

The computer-based simulation of fluid and thermal dynamics is commonly referred to

as Computational Fluid Dynamics or CFD. This technology has more than 40 years of

history in the realms of academic research, corporate R&D, and general engineering.

Traditionally CFD is used by an engineering specialist, someone that has deep subject

matter expertise and serves as an internal resource for the product development

organization. In this arrangement the CFD specialist replicates the duties of the physical

lab manager but uses a digital tool set. They take the model from engineering, convert it

to a simplified, representative prototype, run the analysis and report the findings. The

process is both labor and time intensive so it is often reserved for reliability engineering,

i.e. finding out why the design failed in the physical test.

P&G’s Tom Lange calls this “pathology work” and considers it the low end of potential

for virtual study. “Reliability engineering makes broken systems work faster, rather than

designing optimal systems from the beginning.”

This misaligned application of digital prototyping is focused on efficiency during crisis

situations not the greater mission of effectiveness. Best in class companies seek a

different, higher value return on their investments. As a result they are adopting CFD and

other digital simulation tools developed specifically for proactive engineering or upfront

design optimization.



requiremenTs for effecTive DigiTal flow anD

Thermal ProToTyPing

Best in class companies have shown a willingness to adopt new technologies if it serves their

mission: giving their customers more of what they want. In the case of fluid flow and heat

transfer simulation, this means integration within the design engineering process.

By creating a collaborative, digital design study environment more knowledge is gained and

applied when the cost of change is lowest, translating into a more robust, innovative design

that maximizes revenue and profitability through the entire product lifecycle.

Practically speaking for most organizations, effective digital flow and thermal prototyping

requires CFD to function in concert with a 3D CAD system to enable the digital testing of

numerous scenarios as part of an interactive design study. This category of technology is

commonly referred to as upfront CFD.



The enablers of uPfronT cfD

CAD-driven Process: The design environment for best in class companies is 3D CAD and

there are many advantages to extending this environment for simulation. It’s important to

note that this doesn’t imply all simulation must be done within, or embedded in, the CAD

interface.

Limitations of CAD-embedded simulation

1. The CAD interface often lacks the visualization, design study, and decision-making

tools necessary for simulation users to achieve project goals and organizational

effectiveness.

2. The CAD interface actually limits the number and pace of functionality

and innovation available to simulation users.

No matter what interface the CFD solution uses it is important to confirm it leverages

the native geometric model plus the relevant engineering information associated with

the model.

- Leverage native geometric model

- Use and protect the relevant engineering information associated with the CAD model

- User interface, mouse commands, and workflow should mimic or emulate those

in CAD

making design decisions

from 3D simulation data

requires a flexible, interactive

design study environment

CAD-driven simulation

maximizes the value of

CAD data while supplying

an environment optimized

for design study and

decision-making.



Design Study Environment: CFD supplies much more design performance data than

physical testing; instead of data from a few probes, data is available at every conceivable

location. More importantly, this data can be produced for dozens of 3D design scenarios.

Without a well constructed design study environment in which to visualize this mountain

of simulation data organizational effectiveness is more likely to be hindered than helped.

Built-in Intelligence: Shifting fluid flow and heat transfer simulation from the CFD guru to

the design engineer requires much of the know-how possessed by the guru to be supplied

to the design engineer in the form of built-in intelligence, i.e. the software automates many

of the decisions and tasks related to the CFD process, leaving the engineer to focus on de-

sign performance and its optimization.

Decision and Task Automation Checklist:

Flow volume creation – CFD simulations require a representation for all the physical •

space within or around the CAD assembly. This is done via a Boolean extraction from

the CAD model to represent it and is referred to as the flow region in the simulation;

this procedure can become a real bottleneck for design engineers unless it is fully

automated.

Mesh generation – all forms of simulation require the geometric model to be broken •

down into discrete sections (i.e. mesh elements) so the flow and thermal dynamics in

that area can be accurately calculated. Realistically, if engineers are asked to accept

ownership for this prerequisite the use of simulation is often abandoned. For this

reason the meshing task must be fully automated. CFD packages using the Finite

Element Method tend to provide the highest level of meshing automation.



Mesh refinement – in specific areas of the model the density of mesh elements must •

be refined to ensure accurate simulations results; most design engineers simply don’t

possess the know-how for this procedure so it’s vital that upfront CFD software do it for

them.

Solver selection – selecting solvers is the bane of mathematicians and physicists not •

design engineers; every CFD package includes a wide array of solvers which may be

necessary at specific moments in the simulation process; a good upfront CFD package

fully automates this selection process and makes it invisible to the engineer.

Solution convergence – With so many complex computations taking place how does the •

user know when the simulation results are ready for review? Most engineers err on the

side of caution and run the simulation for hundreds of iterations more than is neces-

sary. Modern upfront CFD systems monitor the convergence process and notify the

engineer when results are ready.

Solution Scope: CFD is only useful if it can simulate the flow and thermal dynamics that

impact the performance of the product being designed. This requirement is often the

greatest worry among engineers but in most situations it is unwarranted. After more than

40 years of commercial development the technology has become comprehensive and quite

standardized. Within the upfront CFD category most products provide the necessary

solution scope for most engineering projects. The areas of wider discrepancy have

already been noted in the upfront CFD enablers.



conclusion

Peter Drucker maintained the best way to predict the future is to invent it. In this Internet

age Drucker’s ideas are more relevant than ever. Technologies like digital prototyping are

a minimum requirement to achieve the agility and innovation mandated by the corporate

mission.

For companies engineering systems or products for a flow and thermal world,

upfront CFD opens the door to shift from efficiency to effectiveness.

If you have any questions or wish to gain

further info, please contact us:

World Headquarters

Blue Ridge Numerics, Inc.

United States

+1 434 977 2764

United Kingdom

Blue Ridge Numerics Limited

+44 1628 501501

Germany

Blue Ridge Numerics GmbH

+49 (0) 641 4990 186

China

Blue Ridge Numerics China

Tel: +86 10 64867195

Japan

CFdesign Japan K.K.

+81-3-4530-3809

India

CFdesign Software India Pvt Ltd

+91 80 4060 0708

www.cfdesign.com

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Upfront CFD Buyers Guide