I am modifying OpenFVM to deal with the neutron diffusion equation. The equation consists of a second order elliptic operator, in a way identical to the viscous diffusion term in the momentum equation. I noticed that when I perform the non-orthogonal correction, the code "blows up" if I divide the cell-center gradient by the volume of the mesh (Vp). If I don't divide by it, everything seems to be fine, meaning I get convergence and the results "make sense" compared to a case where I do not apply any non-orthogonal correction.
Any clues?
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Non-orthogonal corrections tend to make the solution more unstable because it adds "weight" to the source term. With non-orthogonal corrections it might be necessary to reduce the time step significantly.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I am modifying OpenFVM to deal with the neutron diffusion equation. The equation consists of a second order elliptic operator, in a way identical to the viscous diffusion term in the momentum equation. I noticed that when I perform the non-orthogonal correction, the code "blows up" if I divide the cell-center gradient by the volume of the mesh (Vp). If I don't divide by it, everything seems to be fine, meaning I get convergence and the results "make sense" compared to a case where I do not apply any non-orthogonal correction.
Any clues?
Non-orthogonal corrections tend to make the solution more unstable because it adds "weight" to the source term. With non-orthogonal corrections it might be necessary to reduce the time step significantly.