[seb62]

Hi all,

I was working on a turbulent flat plate with the
Spalart Allmaras model, and the results were not fine.
So I had a look at the source code and I think there is something wrong.
The version implemented in openFOAM 1.5 is the Spalart Allmaras with fv3 function. This version
also requires to modify fv2, which is not done (the correct fv2 consistent with the use of fv3 is on the commented line) :


tmp<volscalarfield> SpalartAllmaras::fv2
(
const volScalarField& chi,
const volScalarField& fv1
) const
{
return 1.0 - chi/(1.0 + chi*fv1);
//return 1.0/pow3(scalar(1) + chi/Cv2);
}

Thus I think either the commented fv2 should be used keeping fv3 unchanged, or fv3 should be set to 1, keeping fv2 unchanged.
For testing, I did the latter, removing fv3 in the expression for Stilda, which gives the basic form of Spalart Allmaras model :

volScalarField Stilda =
sqrt(2.0)*mag(skew(fvc::grad(U_)))
+ fv2(chi, fv1)*nuTilda_/sqr(kappa_*d_);


After recompiling, the velocity profiles and local friction agree very well with theory and other CFD codes.

Seb