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Old   May 4, 2010, 04:23
Default Viscous Force Calculation
John Wang
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Location: Singapore
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Hi guys,

I'm trying to implement a force-balance type subroutine into the pimpleDyMFoam solver based on the code from forces.C. I am having trouble with the calculation of the viscous force, though, as the forces.C uses the following code for the viscous force:

00438         const volVectorField& U = obr_.lookupObject<volVectorField>(UName_);
00439         const volScalarField& p = obr_.lookupObject<volScalarField>(pName_);
00441         const fvMesh& mesh = U.mesh();
00443         const surfaceVectorField::GeometricBoundaryField& Sfb =
00444             mesh.Sf().boundaryField();
00446         tmp<volSymmTensorField> tdevRhoReff = devRhoReff();
00447         const volSymmTensorField::GeometricBoundaryField& devRhoReffb
00448             = tdevRhoReff().boundaryField();
00450         forAllConstIter(labelHashSet, patchSet_, iter)
00451         {
00452             label patchi = iter.key();
00454             vectorField Md = mesh.C().boundaryField()[patchi] - CofR_;
00456             vectorField pf = Sfb[patchi]*p.boundaryField()[patchi];
00458             fm.first().first() += rho(p)*sum(pf);
00459             fm.second().first() += rho(p)*sum(Md ^ pf);
00461             vectorField vf = Sfb[patchi] & devRhoReffb[patchi];
00463             fm.first().second() += sum(vf);
00464             fm.second().second() += sum(Md ^ vf);
00465         }
since I will only use the solver under incompressible condition, the devRhoReff() should just be rho()*ras.devReff() with ras.devReff() obtained from RASModel.H based on the RAS model in RASProperties.
00059     else if (obr_.foundObject<incompressible::RASModel>("RASProperties"))
00060     {
00061         const incompressible::RASModel& ras
00062             = obr_.lookupObject<incompressible::RASModel>("RASProperties");
00064         return rho()*ras.devReff();
00065     }
As I am not that familiar with the object oriented programming part of C++ (I have just switched over from using C), I am not sure how to define the obr_ objectRegistry pointer. Can someone point me to a source code/thread that contains such information? Thanks

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Old   May 4, 2010, 04:59
John Wang
Join Date: Mar 2009
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Solved... I must have been more sleep deprived than I thought I am...

Anyway, defining the devRhoReff() using rhoInf*turbulence->devReff() did the trick.

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