[Agavi]

Hi everyone,

I'm an openfoam beginner and am trying to implement a simple addition of a term (sp) in the diagonal of the matrix form of the N-S eqns. ie: . The term should be subtracted implicitly in the diagonal of the RHS of Au=b, increasing the diagonal dominance because sp<0. In order to implement this change in OF I used the SuSp framework. I added a term in the PDE in order for it to be discretized as in the matrix form.

I'm using

eqn += fvm::Sp(sp/Vp,U) in the addSup function in fvOptions.

I tried printing out the diagonal and the upper and lower matrices of UEqn and it appears that the diagonal indeed increases by sp, while the upper and lower remain untouched. However I'm not getting my desirable results so I was wondering if there is anything wrong with my implementation.

The reason I'm confused is that I don't seem to be able to print out the system A*u=b. I did find a way online to get matrix A and vector b, by adding the UEqn's upper lower and diagonal with the BC contributions, but when i multiply this matrix by the UEqn().psi() (when the solution has converged) I do not get the UEqn().source(), which is again not equal to UEqn().boundaryCoeffs()[patchI][faceI], which i thought was supposed to be the RHS of Au=b. I am definitely getting something wrong, and probably need some good explanation of the fvMatrix class functions. I'd be very greatful if someone could point me to the right direction

Thanks,

A

[dlahaye]

Replace Sp by SuSp. See https://github.com/OpenFOAM/OpenFOAM...e/fvm/fvmSup.H (and corresponding C-file).

Some details are at https://www.linkedin.com/pulse/openf...menico-lahaye/