# Smagorinsky Coeffs

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 August 15, 2006, 10:32 I have read Dr. Weller's paper #1 New Member   futoshi tanaka Join Date: Mar 2009 Posts: 3 Rep Power: 8 I have read Dr. Weller's paper to study LES modeling by OpenFOAM. This paper is [A comparative study of subgrid scale models in homogeneous isotropic turbulence in Phys. Fluids 1997]. Smagorinsky coeffs in OpenFOAM are Ce=1.05 and Ck=0.07. What are these parameters ? Dr. Weller's paper have used CI=0.202 and Cd=0.042(Cs=0.2=sqrt(Cd)?).

July 21, 2010, 02:51
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Jie
Join Date: Jan 2010
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Quote:
 Originally Posted by ftanaka I have read Dr. Weller's paper to study LES modeling by OpenFOAM. This paper is [A comparative study of subgrid scale models in homogeneous isotropic turbulence in Phys. Fluids 1997]. Smagorinsky coeffs in OpenFOAM are Ce=1.05 and Ck=0.07. What are these parameters ? Dr. Weller's paper have used CI=0.202 and Cd=0.042(Cs=0.2=sqrt(Cd)?).
Hi ftanaka

Have you got the reference for the dynSmagorinsky model used in OpenFOAM by any chance? I am stuck at the same place trying to understand it as it is different from the original dynamic Smagoribsky from Lilly 1992.

Thanks

 September 3, 2010, 12:07 #3 New Member   Matt James Join Date: Jun 2010 Location: Marinette,WI, USA Posts: 25 Rep Power: 7 at the tail end of the thread "How to use dynSmagorinsky correctly" folks are discussing how the OpenFOAM implementation differs from the "real" method laid out by Germano. From what I've read, it looks as though OpenFOAM-dynSmag calculates the coefficient but averages it over the entire domain (and thus having a domain-constant eddy viscosity) rather than over wall-parallel planes as was intended by the original model. In summary, the openfoam version is time-varying rather than time and y varying.

 September 3, 2010, 12:08 #4 New Member   Matt James Join Date: Jun 2010 Location: Marinette,WI, USA Posts: 25 Rep Power: 7 And I have NO idea why the OpenFOAM dynamic Smagorinsky model requires a coefficient! Maybe it sets the second filter size?

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