CFD Online Discussion Forums - divdevreff in GenEddyVisc and GenSGSStress

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)

- OpenFOAM Running, Solving & CFD (https://www.cfd-online.com/Forums/openfoam-solving/)

- - divdevreff in GenEddyVisc and GenSGSStress (https://www.cfd-online.com/Forums/openfoam-solving/137825-divdevreff-geneddyvisc-gensgsstress.html)

divdevreff in GenEddyVisc and GenSGSStress

Hi, everyone!

I am confused about the difference between the expressions of divdevreff in GenEddyVisc and GenSGSStress.

In GenEddyVisc,

Code:

tmp<fvVectorMatrix> GenEddyVisc::divDevReff(volVectorField& U) const

{

    return

    (

      - fvm::laplacian(nuEff(), U)

      - fvc::div(nuEff()*dev(T(fvc::grad(U))))

    );

}

In GenSGSStress,

Code:

tmp<fvVectorMatrix> GenSGSStress::divDevReff

(

    volVectorField& U

) const

{

    if (couplingFactor_.value() > 0.0)

    {

        return

        (

            fvc::div(B_ + couplingFactor_*nuSgs_*fvc::grad(U))

          + fvc::laplacian

            (

                (1.0 - couplingFactor_)*nuSgs_, U, "laplacian(nuEff,U)"

            )

          - fvm::laplacian(nuEff(), U)

        );

    }

    else

    {

        return

        (

            fvc::div(B_)

          + fvc::laplacian(nuSgs_, U, "laplacian(nuEff,U)")

          - fvm::laplacian(nuEff(), U)

        );

    }

}

I think B is neglected in the expression from GenEddyVisc. I find that almost all the eddy viscosity models include GenEddyVisc.H, but none of them includes GenSGSStress.H. Why is B neglected? Will this B make a big difference?

Billions of thanks!

Just forget about this thread, I made a very terrible mistake.............

Quote:

Originally Posted by gxy200992243 (Post 498348)

Just forget about this thread, I made a very terrible mistake.............

Hi,

I have a related question, I hope you can provide me some insight. Why nuSgs is included in GenSGSStress??! I look into the code and I see that nuSgs IO state is set to NO_READ, so how and why it is calculated?!

Thanks,
Syavash