[petsc-users] DMPlex overlap

[Nicolas Barral]

Hi all,

First, I'm not sure I understand what the overlap parameter in 
DMPlexDistributeOverlap does. I tried the following: generate a small 
mesh on 1 rank with DMPlexCreateBoxMesh, then distribute it with 
DMPlexDistribute. At this point I have two nice partitions, with shared 
vertices and no overlapping cells. Then I call DMPlexDistributeOverlap 
with the overlap parameter set to 0 or 1, and get the same resulting 
plex in both cases. Why is that ?

Second, I'm wondering what would be a good way to handle two overlaps 
and associated local vectors. In my adaptation code, the remeshing 
library requires a non-overlapping mesh, while the refinement criterion 
computation is based on hessian computations, which require a layer of 
overlap. What I can do is clone the dm before distributing the overlap, 
then manage two independent plex objects with their own local sections 
etc. and copy/trim local vectors manually. Is there a more automatic way 
to do this ?

Thanks

--
Nicolas