[petsc-users] modeling a dual mesh

[Matthew Knepley]

On Sat, Nov 14, 2015 at 6:28 AM, Marco Zocca <zocca.marco at gmail.com> wrote:

> What construct can I use to build and keep track (i.e. map over) a
> staggered index set, i.e. the dual (vertices, elements) meshes for a FEM
> application.
>
> I am looking for the equivalent, on a regular mesh, of the `sieve`
> construction (
> http://www.mcs.anl.gov/petsc/documentation/tutorials/sieve.pdf , which I
> understand to be only available for DMPLEX).
>
> I could hack together my own by using DM and IS, but I'd first like to be
> sure about the non-existence of current implementations.
>

1) Everyone who has done this in PETSc just uses another DMDA and some
buffer cells

2) I think the right way to do this is to have a canonical numbering for
the pieces of a DMDA and use PetscSection. I wrote a bunch
    of support for this, which allows arbitrary partitioning, staggered and
PIC (and DG) discretizations, and FEM-style residuals. However,
    no one cared because using multiple DMDAs is so easy.

   Matt


> Thank you in advance,
>
> Marco
>
-- 
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
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