CFD Novice to Expert Part 7: CFD 201

Hopefully you had a successful time simulating your application with the advice served up in "CFD Novice to Expert Part 6: CFD For Your Application." Before I finish up this 7 part series I want to offer some parting thoughts on where and how best to use CFD within a product design cycle.

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CFD 201

Like all modeling techniques, CFD has its strengths and weaknesses. Exactly matching experimental flow results with CFD can be a difficult task - a prime example is trying to match experimental drag predictions with CFD.

In pursuit of perfect matches with experiment, often the CFD simulation will become prohibitively expensive in terms of turnaround time and memory requirements. A more pragmatic approach is to acknowledge the limitations of CFD and instead perform comparison studies between different designs to reduce the design options down to the most promising combination of design parameters and then perform a limited set of experimental tests on this subset.

Often CFD is used to analyze an existing design, so the geometry is either overly detailed or worse it is a set of scanned points. The scope to analyze and make modifications to existing designs is limited when compared to the scope you have during the concept design phase.

It is generally agreed that the biggest savings from Computer-Aided Engineering (CAE) analysis, CFD included, are realized through the earlier use of analysis in the design process. The cost of making design changes rises exponentially the further along the product design cycle you progress. The biggest impact of CFD is often to be found during the concept design phase, when the geometry is free from manufacturing constraints (e.g., bolts, wires). The benefits of using CFD here are two fold - the geometry can easily be parameterized to analyze a vast array of shapes, and it doesn't contain extraneous details, which can require a large effort to de-feature ready for analysis.

Graduation

Congratulations, you are now well on your way to CFD expert status. Of course each area I've mentioned has plenty of scope for more learning - all the way up to the PhD level if you are so inclined. Also to get a better understanding of some specialist areas of CFD, courses such as those offered by the AIAA or NAFEMS might be worth considering.

Now it's time to spread your virtual CFD wings and go solve that energy crisis - good luck!

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