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divdevreff in GenEddyVisc and GenSGSStress

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Old   June 23, 2014, 16:27
Default divdevreff in GenEddyVisc and GenSGSStress
  #1
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Xiangyu Gao
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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!
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Old   June 23, 2014, 21:07
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  #2
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Xiangyu Gao
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Just forget about this thread, I made a very terrible mistake.............
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Old   July 28, 2016, 18:23
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Ehsan Asgari
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Quote:
Originally Posted by gxy200992243 View Post
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
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