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-   -   understanding kEpsilon model source code (http://www.cfd-online.com/Forums/openfoam-programming-development/69893-understanding-kepsilon-model-source-code.html)

jet November 8, 2009 13:55

understanding kEpsilon model source code
 
Hi,

I have a question about the implementation of the kEpsilon source code in the file kEpsilon.C (.../src/turbulenceModels/incompressible/RAS/kEpsilon). In line 181 the divDevReff()-function is declared. Can anybody explain the code in line 185 and 186 to me?

Thanks!

chingyinh November 11, 2009 23:25

Can you post that lines out?

jet November 14, 2009 17:22

Hi, I don't understand the following lines:

return
(
-laplacian(nuEff(), U)
-div(nuEff()*dev(grad(U)().T()))
);

The whole expression is defined as divDevReff() and should return the source term for the momentum equation. I tried to write it down mathematically but I failed!

Thanks for your help!

sega November 15, 2009 05:14

Some people don't know that dev() is a transposition!
Well - at least it was me who doesn't know until I was told.

But what is this T() ?

jet November 15, 2009 09:21

Hmm, are you sure that dev() is a transposition? I think that .T() is a transposition and dev() ist the deviatoric component ( tensor -1/3*(trace tensor)*I ) of the tensor grad(U)().T()?

But I wonder if dev() shouldn't be dev2()?

sega November 15, 2009 09:52

Actually your statement makes more sense.
I haven't thought about the fact that grad(U) is a tensor and not a vector like U itself!


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