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
