Poisson Eqn in a concentric cube

[Sean Dettrick]

Just curious ... to reduce the matrix size, is it possible to build a
nullspace using the cutout points, and then remove that nullspace from
the matrix constructed from the DA?  Or does that have some other
effect?

Thanks,
Sean




Currently, the DA does not directly support cutout grids, as you have
shown above. However, you could just substitute the identity for all
points in the cutout, and only suffer from an excessive preallocation.
Does this make sense?

 Thanks,

    Matt

On 7/23/07, #DOMINIC DENVER JOHN CHANDAR# <DOMI0002 at ntu.edu.sg> wrote:
>
>
> Hi,
>
>      I would like to solve the Poisson equation (3D) in a concentric type of
> cube as in the attached figure using PETSc. The solution domain would be the
> shaded region only and it extends inside the cube. I would like to have
> suggestions on ways to form and assemble the matrix associated with the
> discretization. Also, is it a good practise to discretize the entire domain
> and blank the grid points which are within the cube not in the domain ?
>
> Regards,
> Dominic
>
>


-- 
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