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Jeff Bodner, United Defense January 22, 1999 13:34

Your opinion on low speed codes
Our company will be looking for a code for general purpose incompressible applications (buoyancy driven flows, HVAC, electronics cooling, unstructured mesh). I would welcome any suggestions on which commercial codes you prefer for these applications. Since I don't want to fill the board with advertisements or start arguments, I would prefer email reponses, especially from individuals with associations to commercial vendors. Thanks.

John C. Chien January 22, 1999 14:38

Re: Your opinion on low speed codes
If I were you, I would be looking for a CFD engineer experienced in those applications first. The CFD engineer would then use whatever codes necessary to solve his problems. Without CFD engineers, the CFD codes are useless. Even if you can find the best CFD code for your applications, 95% of the time it depends on the experience of the CFD engineer to obtain a successful answer. If your company is also looking for solutions to those applications, your engineers must have experience in CAD, mesh generation,solution procedure controls, post-processing, interpretation of CFD results. I think, the CFD code itself is the least important part of the whole CFD activities. Since it is impossible to write an error-free 5000-line code or 10,000-line code, most of the time you will be forced to use several codes to check out the results to make sure that the results are in the same ball park. That is if you are really interested in the CFD results. This is just a general comment for everybody in CFD field.

Jeff Bodner, United Defense January 22, 1999 14:59

Re: Your opinion on low speed codes
Perhaps I should have been a little more clear. We have engineers who are well-versed in CFD, but 90% of our work lies in the high-speed aerodynamic realm (we use NPARC, WIND). We're not satisfied with the code we currently have for the low-speed applications, and are looking for a replacement. I know about the industry-leading packages, and I'm just trying to solicit opinions from the peanut gallery on other alternatives that may be well-suited for the applications I mentioned. Thanks for your response.

John C. Chien January 22, 1999 15:47

Re: Your opinion on low speed codes
Now I understand your real problem and issues. I agree with you that high-speed code normally has problem in low Mach number regime. As a matter of fact, I am running a 3-D compressible flow code at inlet Mach number below 0.1 . It was impossible before, and now I am getting some converged solutions, with distinct odd-even decoupling in static pressure field. If I plot 2-D contour of pressure from odd arrary ( or even array), you get smooth picture. But when I plot the whole pressure field, I see wiggles. I think you are right in selecting incompressible code ( formulation suitable for incompressible flows) for low speed applications. It is faster to get converged solutions and at same time, avoiding the uncertainty in the low Mach number flow using compressible flow formulation. Thanks for your response.

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