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-   -   implement roughness boundary conditions for Spalart-Allmaras (http://www.cfd-online.com/Forums/openfoam-programming-development/65789-implement-roughness-boundary-conditions-spalart-allmaras.html)

wei_wu June 25, 2009 17:34

implement roughness boundary conditions for Spalart-Allmaras
 
Hello, all

I'm a new foamer and need help on this problem.

I'm trying to apply the roughness boundary condition on the wall with S-A model.

the wall boundary condition will be : d(nutilda)/dn=nutilda/(d_+0.03*hs)
where d_ is the distance to the wall, which is a variable in the S_A model
hs is the roughness height

my question is howI can implement this new boundary condition.
here is my thought:
there is one basic fixedGradient boundary condition which maybe is a good prototype for me. I will change the evaluate member function in order to get value of (nutilda/(d_+0.03*hs)) for the gradient of nutilda , but I'm so clumsy at C++ and FOAM right now and don't know how to make it happen.

here is the evaluate function:
__________________________________________________ _______________________
template<class Type>
void fixedGradientFvPatchField<Type>::evaluate(const Pstream::commsTypes)
{
if (!this->updated())
{
this->updateCoeffs();
}

Field<Type>::operator=
(
this->patchInternalField() + gradient_/this->patch().deltaCoeffs()
);

fvPatchField<Type>::evaluate();
}
__________________________________________________ ________________________

Thank you all
Wei


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