[petsc-users] Geometric MG as Solver & Preconditioner for FEM/Spectral/FD

[Shiva Rudraraju]

Hi,

I am planning to study the effects of geometric multigrid method both as a
Solver and Preconditioner on a system of transport problems involving
coupled diffusion + finite strain mechanics. Part of that study will be to
evaluate the performance of FD vs higher order FEM (Both Lagrange and
Spectral elements).

So in this context I have a few questions:
1)  To motivate the use of MG schemes in this coupled system of equations,
I plan to initially implement a Red-Black Gauss Siedel solver for FD to
serve as a benchmark. Is there a good example related to the Red-Black
Gauss Siedel implementation?.
.
2) I plan to implement a higher order Lagrange and Spectral element FEM
code. I found one related example in
petsc/src/ksp/ksp/examples/tutorials/ex59.c. Are there any better examples
of general FEM code implementations.

3) MG is often used as a preconditioner, but are there any examples showing
its use as a solver?. I found a few examples here
http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/concepts/multigrid.html,
but nothing in the current version of those codes refer to any MG
datastructures like DMMG which were part of the earlier versions.

Thanks,
Shiva Rudraraju
Univ. of Michigan Ann Arbor
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