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-   -   Floating point exception using RSM model (http://www.cfd-online.com/Forums/fluent/109568-floating-point-exception-using-rsm-model.html)

Jorg November 20, 2012 23:19

Floating point exception using RSM model
 
Hi, i'm trying to simulate a Circulation control airfoil using the Reinolds Stress Model but I have no experience with it; could anybody giveme some guidelines to get my simulation running?

RodriguezFatz November 21, 2012 04:54

Does your simulation converge with some less complex turbulence model (k-epsilon...)?
PS: RSM behaves like a diva...

Jorg November 21, 2012 19:14

Yes, it converges and behaves well when using k-omega or Spalart Almaras. I think i'm gonna need a very precise setup of the RSM inputs....

RodriguezFatz November 22, 2012 06:22

Hey, I am no expert in RSM, but I have a little experience just by trying different turbulence models: In my cases (2d, axisymmetric) the RSM always needed much more cells to work than all other models. Also, I had a few cases, when I never got the RSM working. In your case, I would start by trying to get reasonable values for the RSM boundary conditions at the inlet. If this doesn't work, you could refine your mesh to some unimaginably superb degree and see if that works...

Far November 22, 2012 09:23

It requires higher mesh quality specially cell aspect ratio (~10 or less)


See this thread for details http://www.cfd-online.com/Forums/cfx...nvergence.html

Jorg November 23, 2012 13:39

thanks for your help, i'll try to get higher mesh resolution and let's hope it works. Im concerned about the amount of elements i'll have to define in the flow direction of the boundary layer region to achieve such AR values...


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