[petsc-users] Structured grid in DMPlex?

[Matthew Knepley]

On Thu, May 7, 2015 at 10:31 PM, Justin Chang <jychang48 at gmail.com> wrote:

> Hello everyone,
>
> If I know for a fact that I will be using structured grids AND still want
> the DMPlex data structure, what's the best/fastest way of achieving this?
> Should I:
>
> a) Invoke DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE,
> DM_BOUNDARY_NONE,DMDA_STENCIL_BOX,-3,-3,PETSC_DECIDE,PETSC_DECIDE,1,1,NULL,NULL,&da);
> to get the parallel cell-vertex layout and (somehow) translate this into a
> DMPlex?
>
> b) Manually set the local DMPlex chart/DAG and assign the SF along the
> appropriate processors?
>
> c) Invoke some DMDA/DMPlex function or set of functions that already exist
> for this purpose?
>

It was supposed to work the same way as DMPlex in that you create the DM
and a DS, and then
the Section is created automatically. However, there is so much DA specific
stuff coded and no
one really wanted to use it, so its not maintained or consistent.


> d) Something else?
>

RIght now, I think the best thing to do is use DMPlexCreateHexBoxMesh(),
which gives you a structured mesh. Get
everything in your code working. Then, if you really feel limited by the
mesh structure, we can make the DMDA code
work.

  Thanks,

     Matt


> I know I could just input or create a coarse DAG and invoke -dm_refine,
> but I was wondering if there is an alternative to this method.
>
> Thanks,
> Justin
>



-- 
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
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