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Accessing C_mu within UDF

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Old   July 3, 2014, 05:26
Question Accessing C_mu within UDF
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Jack Chilvers
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Dear All,

I would like to access the parameter C_{\mu} for use within a Fluent UDF. To this end, could somebody please tell me the variable name such that:

cmu = <???>(cell_index, cell_thread);


Many thanks,
Jack
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Old   July 3, 2014, 07:48
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Manuel
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Well, maybe you can compute from its definition. But I don't know if you can access the viscous turbulence if you're not using Spalart-Allmaras. Maybe this works: (Cmu=turb.visc / density / K^2 * epsilon )

Code:
cmu=C_NUT(c,t)/C_R(c,t)/C_K(c,t)/C_K(c,t)*C_D(c,t);
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Old   July 3, 2014, 11:14
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Don't you mean C_MU_L(c,t)?
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Old   July 3, 2014, 12:31
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Manuel
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I have had a better look to the manual and saw that the turbulence eddy viscosity is given by C_MU_T(c,t).

So I correct what I said in previous post, you may compute c_mu as:

cmu=C_MU_T(c,t)/C_R(c,t)/C_K(c,t)/C_K(c,t)*C_D(c,t);

But I wonder... don't you set this parameter as a constant in the turbulence model panel? Why do you need to find it for a specific cell?
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Old   July 19, 2017, 13:12
Default CMU access macro
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Vedamt Chittlangia
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vcvedant is an unknown quantity at this point
CMU is defined as constant in GUI panel so you can directly put its value in the UDF.

I want to modify CMU value as a local variable. I could not find any macro to do this so I used DEFINE_TURBULENT_VISCOSITY() and put my CMU definition there. But the problem seems that this does not suppress the CMU value that is already present in the viscous dialog box of GUI panel.

Can someone help me?

Thanks
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