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Any weakness or limits of CFX for secondary flows

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Old   March 7, 2003, 14:41
Default Any weakness or limits of CFX for secondary flows
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J.T.
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Any one has the epxerience of running the turbulent secondary flows by using CFX? Thanks
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Old   March 9, 2003, 17:11
Default Re: Any weakness or limits of CFX for secondary fl
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Glenn Horrocks
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Hi JT,

I think you'll find that CFX5 is actually one of the best commercial codes around for solving things like secondary flows. It is simulations like that where the the coupled solver in CFX5 really shows its strength over the usual uncoupled technique.

If you are talking about CFX4, well it can solve these types of flows but the simulation time will probably be considerably longer due to its use of the uncoupled solver.

Depending on exactly what turbulent secondary flow you are talking about, you may require the Reynolds stress model to simulate it. CFX 4 and 5 both have a number of Reynolds stress models available. The new CFX 5.6 beta version also contains a stress-omega model which I am yet to try out, but looks interesting for low Reynolds number secondary flows.

Glenn Horrocks
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Old   March 12, 2003, 19:39
Default Re: Any weakness or limits of CFX for secondary fl
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J.T.
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Thank you very much for the infomation! I looked into CFDesign, their results for backward facing step for 3-D turbulent flows are not very good. I am trying to use CFX. Is that easy to get started if you got a pretty complicate geometries? In other word, is their mesh generation automatic or user-friendly? How do you like their post-processor?

Thanks!
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Old   March 12, 2003, 22:21
Default Re: Any weakness or limits of CFX for secondary fl
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Peter
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The automatic mesh generation in CFX5 still needs a lot of improvement. If your geometry consists of the curved surface or fillet, then you may find that the mesh elements will tend to squish together at this region when you use CFX5 mesh generator. The louisy mesh may destroy the whole solution depending on what problems you have. What I suggest to you is to try importing your mesh from other mesh generation software and solve your problem in CFX5. It does have some excellent solvers anyway.
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Old   March 13, 2003, 14:11
Default Re: Any weakness or limits of CFX for secondary fl
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J.T.
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Hi, Peter Did you check their benchmark test with turbulent flow over a 3-D lid-driven cavity? I will ask them to provide the tested results. Since ANSYS bought the CFX, do you think ANSYS's mesh generation will provide best results? If I got the answers I will discuss with you. Thanks!
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Old   March 16, 2003, 10:52
Default Re: Any weakness or limits of CFX for secondary fl
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Robin
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Hi Peter,

Bunching such as this can easily be fixed by setting proper mesh controls.

Robin
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