On Sun, Dec 24, 2017 at 3:43 AM, Mohammad Hassan Baghaei <
[email protected]> wrote:
> Hello
>
> I am using the DMPlex interface for the solving PDEs.
>
Great. What discretization are you using?
> A part of mesh, considering, is staggered grid, at the location of middle
> of each edge.
>
So you would like to put variables at each edge midpoint?
> After generation of main grid points, I find it hard to have the staggered
> grid at the prescribed location.
>
In Plex, the topology is specified by the DMPlex, but the dof layout is
specified by a PetscSection. To put
variables on edges, you could use:
DMGetDefaultSection(dm, &s);
DMPlexGetDepthStratum(dm, 1, &eStart, &eEnd);
for (e = eStart; e < eEnd; ++e) {
PetscSectionAddDof(s, e, 1);
}
and of course any other dofs you are using.
> I want to know how to deal with the staggered besides of main grid. Is it
> better to have another DM for the staggered?
>
Another option is to use several DMDA. This has its own drawbacks.
> Is it possible to extend the DMChart and inserting the points.
>
If the chart does not have edges, it is because it has not been
interpolated. Either pass the PETSC_TRUE, or call
http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DMPLEX/DMPlexInterpolate.html
Thanks,
Matt
> I would really appreciate for your time.
>
> Amir
>
--
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.caam.rice.edu/~mk51/>
