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

alanfei · November 17, 2017, 13:45

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!

LuckyTran · November 17, 2017, 15:37

Quote:

Originally Posted by alanfei

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.

November 17, 2017, 13:45	How do I decide Cmu, C1, C2 values of standard k-epsilon model	#1
alanfei New Member Join Date: Nov 2017 Posts: 2 Rep Power: 0	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! fredericgaillard likes this.

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