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-   -   Symmetry model half or total geometrical model in LES (http://www.cfd-online.com/Forums/openfoam-pre-processing/62216-symmetry-model-half-total-geometrical-model-les.html)

 vvqf March 21, 2006 11:34

hi dear all, if the model i

hi dear all,

if the model is symmetric, can we use just half geometrical model in LES ?
as i remember in the tutorial, it is ok for turbFoam, but i am not sure in OpenFoam if it's also ok for LES.

Thanks

 pierre March 21, 2006 14:52

Do you mean the geometry of th

Do you mean the geometry of the domain is symmetric? In which case your computational domain can be reduced as long as the 3D eddy structures of turbulence resolved by the LES model can be captured correclty, it's very case dependent. I.e. in pipes, bad idea. In a backward step case, the width should be as large as necessary, and so on.

Pierre

 vvqf March 22, 2006 08:31

Hi Pierre, Thanks for the an

Hi Pierre,

Geometry for LES
"Even though there might be symmetries in the geometry and flow, the geometrical model should include the full region, since, while the time averaged flows may be symmetric, the instantaneous flows are not, and restricting the domain could constrain the turbulence. Two-dimensional approximations are particularly poor. "

It talks about the general case in CFX, I think in OpenFoam it might be simlilar.

 vivekcfd March 22, 2006 10:06

Never think of simplifying a g

Never think of simplifying a geometry when you are using LES. What ever code it is, LES has to be with full realistic geometry. There is no chance that the instantaneous fields are symmetric in a full turbulent case.
VK

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