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-   -   Turbulence Model Problems (http://www.cfd-online.com/Forums/fluent/74301-turbulence-model-problems.html)

ttlg March 29, 2010 18:31

Turbulence Model Problems
 
Hello All
I'm having a problem on Fluent when I switch from k-e r to a k-w sst model. When I used the k-e model I had no problems and I obtained a solution fine. Now that Ive changed to the k-w sst my solution keeps diverging although everything else is kept the same from the previous model. Any ideas of why this is and how to solve it?

Thanks for your help

Philipov March 30, 2010 02:02

turbulent models must be chosen according to the flow type. The mesh need to be changed too...

heidar April 8, 2010 04:54

heidar
 
in fluent the K-w turbulence model uses one eqution model to resolve the flow structure near wall. whereas the K-e model can uses the 3 type of near waal solution. using one eqution model for near wall treatments leads us to beter results but u have to increase the mesh density.
ok go on and increase mesh density
but be care that now u could not compaire the two answer of K-e and K-w.
bye :D

alikami May 3, 2010 04:26

Yplus
 
Check values of yplus ....
If you have seperated flow try SST but be sure to have low yPLUS ~1 (i guess).

SST uses kw in near wall and ke in inner region ....
In case you dont have seperation better use ke , computationally good
Regards
Ali


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