[petsc-users] DMPlex overlap

[Nicolas Barral]

On 31/03/2021 17:47, Matthew Knepley wrote:
> On Sat, Mar 27, 2021 at 9:27 AM Nicolas Barral 
> <nicolas.barral at math.u-bordeaux.fr 
> <mailto:nicolas.barral at math.u-bordeaux.fr>> wrote:
> 
>     Hi all,
> 
> 
> I promise to read this today. While I am doing that, I have a branch
> 
> https://gitlab.com/petsc/petsc/-/commits/knepley/feature-plex-vertex-mapping
> 
> which I think does the face labeling you want, but I have not tested it yet.
> 
Thanks Matt, I'll have a look later today :) I also have working code 
for what I need - maybe itś  time to share my branch even if it's still 
in progress.

Thanks

-- 
Nicolas

>    Thanks,
> 
>      Matt
> 
>     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
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their 
> experiments is infinitely more interesting than any results to which 
> their experiments lead.
> -- Norbert Wiener
> 
> https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>