[petsc-users] removing cells from existing DMPLEX

[Matteo Semplice]

On 08/06/2018 20:43, Matthew Knepley wrote:
> On Fri, Jun 8, 2018 at 5:10 AM, Matteo Semplice 
> <matteo.semplice at unito.it <mailto:matteo.semplice at unito.it>> wrote:
>
>     Hi.
>
>     We are developing a ghost-fluid type scheme, so we start creating
>     a (cartesian) grid and then "mark" some cells in which the
>     evolution actually takes place and solve a PDE only there.
>
>     We currently handle the grid via a DMPLEX, we through a Label that
>     marks the fluid cells we define a trivial operator for the
>     non-fluid part of the grid, but of course the dofs attached to
>     those cells and faces are still there in the Vec's and in the output.
>
>     We know that (sometimes large) portions of the original grid will
>     never be touched during the evolution, so we would like to remove
>     those from the DMPLEX before partitioning it. Is there a simple
>     way to do it? Ideally automagically via a Label or an IndexSet...
>
>
> Can this do what you want?
>
> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DMPLEX/DMPlexFilter.html
>
> If so, I would caution you that no one uses this right now, so it 
> might forget to do something (say edit out all those
> things from existing labels). I will fix anything that gives you a 
> problem.
>
>   Thanks,
>
>     Matt

It looks like it is exactly what I was looking for. I'll give it a go.

Thanks!

Matteo
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