Is there a way (manual or otherwise) to unrefine a mesh back to its original parent mesh in specifically marked regions?
The closest I've found is implemented in the MeshHierarchy class, which has an coarsen method (along with refine) that can take cell markers as an argument, but it seems to only work when unrefining areas that were refined in the most recent refinement.
The other coarsening method (LocalMeshCoarsening.cpp) that others have mentioned doesn't appear to be exposed in the Python interface, as far as I can tell (is there an easy way to expose it? I'm fine with recompiling).
Thanks.