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 lfgmarc July 14, 2012 20:25

Hi, I have a question about the UEqn implemented into sonicFoam, the code of the UEqn is:

Code:

 fvVectorMatrix UEqn (     fvm::ddt(rho, U)     + fvm::div(phi, U)     + turbulence->divDevRhoReff(U) );
My question is about the term that is computed from the turbulence model, i.e if K-epsilon model is selected, this term results:

Code:

 tmp<fvVectorMatrix> kEpsilon::divDevRhoReff(volVectorField& U) const {     return     (       - fvm::laplacian(muEff(), U)       - fvc::div(muEff()*dev2(fvc::grad(U)().T()))     ); }
Initially I thought that it corresponded to

but after examining the definition of dev2 in src/OpenFOAM/primitives/Tensor/TensorI.H

I found the following:

is the rate-of-strain tensor given by

but according to the definition of DivDevRhoReff

And manipulating the expression (1) I conclude that the term

Code:

     + turbulence->divDevRhoReff(U)
does not correspond to (1).

 haze_1986 January 24, 2013 12:26

Quote:
 Originally Posted by lfgmarc (Post 371474) Hi, I have a question about the UEqn implemented into sonicFoam, the code of the UEqn is: Code:  fvVectorMatrix UEqn (     fvm::ddt(rho, U)     + fvm::div(phi, U)     + turbulence->divDevRhoReff(U) ); My question is about the term that is computed from the turbulence model, i.e if K-epsilon model is selected, this term results: Code:  tmp kEpsilon::divDevRhoReff(volVectorField& U) const {     return     (       - fvm::laplacian(muEff(), U)       - fvc::div(muEff()*dev2(fvc::grad(U)().T()))     ); } Initially I thought that it corresponded to but after examining the definition of dev2 in src/OpenFOAM/primitives/Tensor/TensorI.H I found the following: is the rate-of-strain tensor given by but according to the definition of DivDevRhoReff And manipulating the expression (1) I conclude that the term Code:      + turbulence->divDevRhoReff(U) does not correspond to (1). If someone can help me with my confusion about this term, I was very thankful
Indeed, I was thinking it should be dev instead of dev2 as well if the explanation by poplar in http://www.cfd-online.com/Forums/ope...tml#post388688 is correct.

I hope I can find out what is wrong.

 jens_klostermann February 15, 2013 09:07

Hi,

the term

is equal to

But I miss the term

in
Code:

turbulence->divDevRhoReff(U)
maybe someone can comment on this hidden term?

Jens

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