[petsc-users] Semi-coarsening for GMG using DMDA?

[Joe Alexandersen]

Dear PETSc developers,

We are working with a code that uses regular meshes (DMDA) and geometric multigrid. We would like to go from uniform coarsening/refinement to semi-coarsening/refinement, due to anisotropy in our underlying equations. We have tried to figure out if we can do this using built-in functions of PETSc, but it is unclear to us whether we can get it done relatively easily.

It seems that we can go from the coarsest grid and refine differently in each direction using DMDASetRefinementFactor and then use DMRefine to define the finer levels. However, from the doc page for DMCreateInterpolation, it states that it only works for "uniform refinement" which to me seems to indicate it will not work with different refinement in each direction. But on the other hand, it states that it should work if using DMRefine, which I assume used the information from DMDASetRefinementFactor upon creation?

So our questions are: is there are feasible and relatively simple way to do semi-coarsening/refinement of DMDAs for geometric multigrid hierarchies? Would the above work?

Thanks in advance!

Sincerely,
Joe Alexandersen
University of Southern Denmark

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20250320/5b9a05d7/attachment.html>