[petsc-users] Boundary condition IS

[Matthew Knepley]

On Thu, Dec 7, 2017 at 2:23 AM, Mohammad Hassan Baghaei <
mhbaghaei at mail.sjtu.edu.cn> wrote:

> Hello
>
> I am using DMPlex to construct a fully circular 2D domain for my PDEs. As
> I am discretizing the PDEs using finite difference method,
>

How do you do FD on an unstructured mesh?


> I need to know , to define the layout of PetscSection, how I can find the
> boundary condition IS. I know the location of the boundaries in Sieve
> chart. However, I noticed that I need to know the Index Set of that
> location. Can I use the Sieve point number for Index Set. It seems I think
> I am not familiar with IS. Can you help me? Thank for your help.
>

I like Yann's response. You can simplify the processing somewhat:

  1) You can use DMPlexLabelComplete() to add in edges and vertices on the
boundary

  2) You can use DMPlexComputeCellGeometryFVM to compute the centroid

  Thanks,

    Matt


> Amir
>



-- 
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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