[petsc-users] Passive DM Variables

[Mark Adams]

You want "auxiliary" variables.

There may be better examples but, try looking at
https://petsc.org/release/src/snes/tutorials/ex12.c.html
And search for "aux".

Mark

On Sun, Aug 28, 2022 at 12:44 PM Nicholas Arnold-Medabalimi <
narnoldm at umich.edu> wrote:

> Hi
>
> I'm working on a finite volume implementation using DMPlex. I was
> wondering what the best-considered way to add cell variables to the DM that
> we don't want to be part of the ksp/snes solve. As far as I can tell, if I
> add an extra section with those, they will still be part of the F and U
> vectors in the solver callbacks (to be expected). But my impression is that
> that will just inflate the system size even if they have an F=0? Or is the
> solver able to notice variables that are not dependent for the solve.
>
> Alternatively, I have been just making a separate DM with those but that
> feels a bit clunky especially if any mesh refinement occurs.
>
> Any advice would be much appreciated.
>
> Thanks
> Nicholas
>
> --
> Nicholas Arnold-Medabalimi
>
> Ph.D. Candidate
> Computational Aeroscience Lab
> University of Michigan
>
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