Dear All,
I am a newbie with CFDEMcoupling code, and I am trying to study the implemented models. At the present I am dealing with the "viscForce" model, and I have a question about how the "divTau" term is computed for compressible flows; the expression I found is the following:
divTauField =
- fvc::laplacian(mufField, U_)
- fvc::div(mufField*dev(fvc::grad(U_)().T()));
What I do not understand is why the "dev" operator is used in place of the "dev2" one.
Does anyone have a suggestion about it?
I thank you all for your attention and help.
Kind regards,
Gabriel
Bruno | Fri, 01/23/2015 - 14:56
Viscforce
That seems to be a mistake. The right operator to use is indeed dev2. (to have grad U + grad U^Transposed - 2/3 div U Identity) and it is correctly implement in the cfdemCloud. However to be honest I do not think this will make much of a difference for anything...
Bruno
xlibp | Fri, 12/25/2015 - 08:55
Calculation of divTauField
Dear all,
In the calculation of viscForce,I did not find the formula Gabriel mentioned:
divTauField =
- fvc::laplacian(mufField, U_)
- fvc::div(mufField*dev(fvc::grad(U_)().T())).
Instead, we have divTauField = forceSubM(0).divTauField(U_) in file viscForce.C.
Could anyone tell me where the exact expression of divTauField() locates?
Besides, I found:
tmp laminar::divDevReff(volVectorField& U) const
{
return
(
- fvm::laplacian(nuEff(), U)
- fvc::div(nuEff()*dev(T(fvc::grad(U))))
);
}
in laminar.C OpenFOAM part. Does divTauField = divDevReff ?
Many thanks for any comments.