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-   -   CFX-11 vs CFX-13 SST Model (http://www.cfd-online.com/Forums/cfx/94924-cfx-11-vs-cfx-13-sst-model.html)

Zigainer November 30, 2011 06:13

CFX-11 vs CFX-13 SST Model
 
Hey,

I'm simulating a two-pass-channel with rectangular geometry.
I've got some previous results with CFX-11 and SST Model. The previous simulation (done by a other person) compares different turbulence models for the same geometry. My CFX-13 results (also done with SST model) are different.
So does anybody know, what ANSYS changed in there turbulence models?
It kind of looks like the CFX-13 SST model uses some elements from CFX-11 SST cc model.
Hope you guys know a little bit more.

Far December 1, 2011 13:26

Well, I dont see any change in SST model

ghorrocks December 1, 2011 17:48

I suspect there have been some small changes in a few of the peripheral models (eg streamline curvature) and the numerics could be different. You would have to either troll through the release notes or contact CFX support to be sure.

Far December 1, 2011 18:04

I ran few cases on CFX 12 and 13 with SST model and same settings (e.g. same mesh, boundary conditions etc) and I didn't find any difference

ghorrocks December 2, 2011 00:46

For almost all cases you won't find a difference. It is only on rare cases that you will find a difference.

Far December 2, 2011 02:42

I would suggest to compare each and every term and constant factor in CFX theory guide of V 12 and 13

Zigainer December 2, 2011 03:18

Thanks guys. I compared the factor in theory guide and there are all the same. I was just wondering about my results (compared to a old study done by a stundent in 2010)

Far December 2, 2011 05:06

Mesh and other settings are same in your study and old resutls?

Zigainer December 2, 2011 05:14

Quote:

Originally Posted by Far (Post 334378)
Mesh and other settings are same in your study and old resutls?

Not quite the same (I don't habe the old mesh). Problem is, that I am doing a conjugated calculation for a ribbed cooling-channel. The older thesis did only simulate the fluid with constant wall-temperature. My results are not very close to the experiment (different contour). The old thesis (turbulence model study) has almost the same contour with SST. But the old SST cc looks quite the same as my SST. And in the end my results for heat transfer are too good (Nu/Nu_0 is almost constantly 0.5 above experiment).

Far December 2, 2011 05:33

SST and SST-CC model are same except in some flow regions where CC model is activated (some triggering factor in production term). Therefore if your problem does not have that sort of region of flow then SST and SST-CC shall behave identically.

Zigainer December 2, 2011 05:40

Quote:

Originally Posted by Far (Post 334388)
SST and SST-CC model are same except in some flow regions where CC model is activated (some triggering factor in production term). Therefore if your problem does not have that sort of region of flow then SST and SST-CC shall behave identically.

Thanks for your help. I probalbly have some of these regions because my channel is ribbed.
So I startet a SST-cc calculation, and then I'll see if there is a difference in CFX-13.


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