[petsc-users] Using DMDAs with an assigned domain decomposition to Solve Poisson Equation

[Mark Adams]

On Mon, Feb 24, 2020 at 5:30 AM Pierpaolo Minelli <pierpaolo.minelli at cnr.it>
wrote:

> Hi,
> I'm developing a 3D code in Fortran to study the space-time evolution of
> charged particles within a Cartesian domain.
> The domain decomposition has been made by me taking into account symmetry
> and load balancing reasons related to my specific problem. In this first
> draft, it will remain constant throughout my simulation.
>
> Is there a way, using DMDAs, to solve Poisson's equation, using the domain
> decomposition above, obtaining as a result the local solution including its
> ghost cells values?
>

https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DM/DMGlobalToLocalBegin.html#DMGlobalToLocalBegin



>
> As input data at each time-step I know the electric charge density in each
> local subdomain (RHS), including the ghost cells, even if I don't think
> they are useful for the calculation of the equation.
> Matrix coefficients (LHS) and boundary conditions are constant during my
> simulation.
>
> As an output I would need to know the local electrical potential in each
> local subdomain, including the values of the ghost cells in each
> dimension(X,Y,Z).
>
> Is there an example that I can use in Fortran to solve this kind of
> problem?
>

I see one, but it is not hard to convert a C example:

https://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex14f.F90.html


>
> Thanks in advance
>
> Pierpaolo Minelli
>
>
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