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How do I decide Cmu, C1, C2 values of standard k-epsilon model

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Old   November 17, 2017, 14:45
Default How do I decide Cmu, C1, C2 values of standard k-epsilon model
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Dear experts,

I am running a case of a 2D rectangle rigid body in a constant velocity flow field (10 m/s) under the standard k-e model and expect to see the karman vortex.

However, the simulation kept becoming diverge when I shrank my mesh size. My adviser suggested me to change the Cmu, C1, C2 values (I am now using the default values which are Cmu=0.09, C1=1.44, C2=1.92 ).

Does anyone know how to find a proper value of Cmu, C1 and C2 of my case? Or can you suggest me where to find the information of modifying the constants.

Many thanks!
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Old   November 17, 2017, 16:37
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Quote:
Originally Posted by alanfei View Post
Does anyone know how to find a proper value of Cmu, C1 and C2 of my case? Or can you suggest me where to find the information of modifying the constants.
The person who suggested modifying the constants should tell you what is the proper values. Otherwise, why the hell did they propose this in the first place?

Besides, I think the default values are already plenty appropriate. I would not change the turbulence model constants. Besides, von Karman vortex shedding dose not really have anything to do with turbulence. You should investigate why your model is diverging, probably your mesh quality is getting worse as you "refine" it.
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