Thank you Jed and Matt. That is exactly what I wanted to do.
I was wondering if there is an example of mapping between DMPLEXs.
I have several requirements of the mapping for my code, such as
- mapping solution vectors on cell-centroids into vertices
- mapping from volume dmplex into sub-dm for wall surface region

Any example will help.

Many thanks,
Mike


Yes, you can use DMPlexCreateSubmesh() (and friends depending on exactly what kind of submesh you want). This will allow you to create a vector over only this mesh, and map your volumetric solution to that subvector. Then you can view the subvector (which pulls in the submesh).

  Thanks,

     Matt

On Mon, Aug 1, 2022 at 10:59 PM Jed Brown <jed@jedbrown.org> wrote:
I would create a sub-DM containing only the part you want to view.

Mike Michell <mi.mike1021@gmail.com> writes:

> Hi,
>
> I am a user of DMPlex object in 3D grid topology. Currently the solution
> field is printed out using viewer PETSCVIEWERVTK in .vtu format. By doing
> that the entire volume components are written in the file. I was wondering
> if there is an option that I can tell PETSc viewer to print out only
> surface component, instead of the entire volume.
>
> Best,
> Mike


--
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