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-   -   Smagorinsky Coeffs (https://www.cfd-online.com/Forums/openfoam-solving/60069-smagorinsky-coeffs.html)

ftanaka August 15, 2006 10:32

I have read Dr. Weller's paper
 
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)?).

jiejie July 21, 2010 02:51

Quote:

Originally Posted by ftanaka (Post 199387)
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

mdjames September 3, 2010 12:07

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.

mdjames September 3, 2010 12:08

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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