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<div class="moz-cite-prefix">On 2019-11-25 7:54 p.m., Matthew
Knepley wrote:<br>
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<div dir="ltr">On Mon, Nov 25, 2019 at 6:25 PM Swarnava Ghosh
<<a href="mailto:swarnava89@gmail.com"
moz-do-not-send="true">swarnava89@gmail.com</a>> wrote:<br>
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<div dir="ltr">Dear PETSc users and developers,
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<div>I am working with dmplex to distribute a 3D
unstructured mesh made of tetrahedrons in a cuboidal
domain. I had a few queries:</div>
<div>1) Is there any way of ensuring load balancing based
on the number of vertices per MPI process.</div>
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<div>You can now call DMPlexRebalanceSharedPoints() to try and
get better balance of vertices.</div>
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<p>Hi Matt,</p>
<p>I just want to follow up if this new function can help to solve
the "Strange Partition in PETSc 3.11" problem I mentioned before.
Would you please let me know when shall I call this function?
Right before DMPlexDistribute?</p>
<p>call DMPlexCreateFromCellList<br>
<br>
call DMPlexGetPartitioner<br>
<br>
call PetscPartitionerSetFromOptions<br>
<br>
call DMPlexDistribute</p>
<p>Thanks,</p>
<p>Danyang<br>
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<div>2) As the global domain is cuboidal, is the resulting
domain decomposition also cuboidal on every MPI process?
If not, is there a way to ensure this? For example in
DMDA, the default domain decomposition for a cuboidal
domain is cuboidal. </div>
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<div>It sounds like you do not want something that is actually
unstructured. Rather, it seems like you want to</div>
<div>take a DMDA type thing and split it into tets. You can
get a cuboidal decomposition of a hex mesh easily.</div>
<div>Call DMPlexCreateBoxMesh() with one cell for every
process, distribute, and then uniformly refine. This</div>
<div>will not quite work for tets since the mesh partitioner
will tend to violate that constraint. You could:</div>
<div><br>
</div>
<div> a) Prescribe the distribution yourself using the Shell
partitioner type</div>
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<div>or</div>
<div><br>
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<div> b) Write a refiner that turns hexes into tets</div>
<div><br>
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<div>We already have a refiner that turns tets into hexes, but
we never wrote the other direction because it was not clear</div>
<div>that it was useful.</div>
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<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
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<div>Sincerely,</div>
<div>SG</div>
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<div>What most experimenters take for granted before
they begin their experiments is infinitely more
interesting than any results to which their
experiments lead.<br>
-- Norbert Wiener</div>
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<div><a href="http://www.cse.buffalo.edu/~knepley/"
target="_blank" moz-do-not-send="true">https://www.cse.buffalo.edu/~knepley/</a><br>
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