[petsc-users] DMPlex with AMR

[Matthew Knepley]

On Sun, Nov 5, 2017 at 1:45 PM, Yann Jobic <yann.jobic at univ-amu.fr> wrote:

> Dear PETSc expert,
>
> I first correctly solve the advection/diffusion equation, with the
> advection/diffusion of a gaussian, in a rotate field.
> I'm using finit element, with PetscFE and the velocity field is in an
> auxillary one, in order to correctly set the residual and the jacobian.
>
> Then, i would like to use p4est, with AMR. To do that, I re-use the
> example : "petsc/examples/src/dm/impls/forest/examples/tests/ex2.c"
> I create a "base" DM, which has everything : PetscFE, PetscDS, the
> boundaries, ... Then, i correctly adapt the mesh, by using :
> ierr = DMForestTemplate(base,comm,&postForest);CHKERRQ(ierr);
> ierr = DMForestSetAdaptivityLabel(postForest,adaptLabel);CHKERRQ(ierr);
>
> My problem is that nothing happens when i'm solving the system, i.e. my
> initial solution does not move, or diffuse.
>
> That would mean that i didn't correctly transfer the problem definition. I
> tried to attach everything to the adapted mesh, without succes.
>
> What is the correct way to transfer the problem definition (PetscFE and
> PetscDS) from one DM to another ?
>

One way to do it is just

 DMGetDS(dm, &prob);
 DMSetDS(newdm, prob);

I think I have this working automatically now in

  knepley/feature-adaptor-plex

Check out the test in SNES ex12

  make -f ./gmakefile test
globsearch="snes_tutorials-runex12_quad_q1_adapt_0"
EXTRA_OPTIONS="-dm_adapt_view hdf5:$PWD/adapt.h5"
  ./bin/petsc_gen_xdmf.py adapt.h5

and then look at adapt.xmf in Paraview. This also works if you try it with
simplicial meshes and Pragmatic, see tri_p1_adapt_1.

  Thanks,

      Matt


> Many thanks in advance,
>
> Regards,
>
> Yann
>
>


-- 
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/>
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