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-   -   which turbulence model is better in turbomachinery ? (http://www.cfd-online.com/Forums/fluent/110938-turbulence-model-better-turbomachinery.html)

Aysiyi December 26, 2012 10:37

which turbulence model is better in turbomachinery ?
 
hi
guys ,i am now simulating a centrifugal compressor in FLUENT 14, in the process , i have a question , which turbulence model is better for turbomachinery? in the fluent training document ,i found that realizable k-ε is recommended in turbomachinery .

so what do you think ? can you share your opinion?
thanks

cric92 December 26, 2012 11:06

There might be no correct answer when RANS is concerned. K-epsilon model is not good capturing separation. Realizable K-epsilon is better then standard K-epsilon. If you can mange y+~1 you should go for SST K-omega.

cfd seeker December 26, 2012 13:07

SST kw is generally recommended for turbo-machinery applications. According to my experience there is always a transition in turbo-machinery flows but 2 Equations RANS models are not capable of predicting transition. However Fluent has introduced two new turbulence models for transition prediction i.e k-kl-w transition (3 eq.) model and Transition kw (4 eq.) model but their mesh requirements are very stringent in the boundary layer(i.e wall y+ <1) and also out of the boundary layer( sufficient mesh resolution in the stream-wise direction and small growth of mesh size away from the boundary layer).
Hope it helps you

Regards

Aysiyi December 26, 2012 21:12

Quote:

Originally Posted by cric92 (Post 399096)
There might be no correct answer when RANS is concerned. K-epsilon model is not good capturing separation. Realizable K-epsilon is better then standard K-epsilon. If you can mange y+~1 you should go for SST K-omega.

i will try ,3k

kbaker March 2, 2013 13:27

I saw new phenomena in FLUENT forum and i m not sure if it exist in other CFD- forums i.e. at the last few days we hear that somebody design a software called it the name he like and start send declarations about it for getting money? I am wondered this forum is free so why these people permitted to ask for money and not share there knowledge (if they really experts) freely? I hope forum moderators give an opinion about this?

Quote:

Originally Posted by cfdman7 (Post 411050)
Hi dears,
Use this interesting new technique: ECFDG
Choosing the Precision and Solver Type, the Turbulence Model and its Options, and the Radiation Model and its Options are the essential parts of many CFD simulations in ANSYS FLUENT software. These selections depend on numerous parameters and interactions between these parameters. Certainly, the most appropriate selection leads the simulation to the most reliable result. ECFDG software pioneers unique forms for these choices. Simply, fill in the forms and send the generated data; afterward, central ECFDG intelligence program will analyze the data and provide an individualized report for your CFD simulation.
www.ecfdg.com



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