[petsc-users] Looking for PETSc Example: Poisson Equation in 2D using FEM - scale upto 1000 procs

[Mark Adams]

There are several but I am updating *src/snes/tests/ex13.c *
<https://gitlab.com/petsc/petsc/-/merge_requests/6875/diffs#diff-content-5a7dc636e85ce214f0a7dcf710f45f1e6800c0d4>
now, in
branch adams/gamg-fast-filter
<https://gitlab.com/petsc/petsc/-/tree/adams/gamg-fast-filter>. but main is
fine (it should get merged very soon).
It does what you want scales forever, but it does not have Neumann BCs.
I might be able to add that, but not today.

Mark

On Mon, Sep 18, 2023 at 11:16 AM Khurana, Parv <p.khurana22 at imperial.ac.uk>
wrote:

> Hello PETSc users,
>
>
>
> Thank you for this very active community of users and the mailing list.
>
>
>
> I am looking for a PETSc example which solves the Poisson equation on a 2D
> domain using FEM (or HO-FEM if possible). I would like the following:
>
>    1. The example should be formulated fully on PETSc, and to be solved
>    with KSP objects in PETSc.
>    2. The problem should scale up to a few hundred processors (ideally
>    1000 procs).
>    3. Ideally on a unit square with either Square or Triangle element
>    discretization.
>    4. There should be an option to specify Dirichlet/Neumann-type BCs on
>    the boundaries.
>
>
>
> I was wondering if someone could point me to such an example as I am
> relatively new to PETSc – and I am trying to avoid reinventing the wheel. I
> have had a look at Examples 29,32,50 and 66 in the PETSc tutorials – while
> they are very close to what I need I am not sure if they scale to a few
> hundred processors. Furthermore, I am aware that I can formulate such a
> problem with FENICS/Firedrake with relative ease and these software
> interfaces with PETSc quite well. However, I am just trying to see if such
> an application already exists purely in PETSc.
>
>
>
> Thanks, and Best
>
> Parv
>
>
>
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