[petsc-users] Identifying mesh points within DMPlex FEM

[Matthew Knepley]

On Mon, Aug 25, 2014 at 2:10 PM, Justin Chang <jychang48 at gmail.com> wrote:

> Hi all,
>
> In the discretization schemes for the DMPlex FEM examples (ex12 and ex62),
> it lets us specify equations as pointwise functions. But what if I wanted
> to assign "regions" to different points within the domain? In one of my
> problems, I want the diffusivity tensor and/or forcing function to differ
> for various layers/regions within the computational domain. I would imagine
> calling something like DMPlexGetLabelValue() to identify a region
> associated with a given mesh point but is it possible to do something like
> this within the f0/f1/g3/etc functions?
>

1) Changing parameters across the domain is straightforward. ex12 does this
for "diffusivity".

2) Changing the function across the domain should probably be accomplished
by changing
     a marker parameter, which is checked inside the function itself.

   Matt


> 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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