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<div class="moz-cite-prefix">On 2019-11-26 10:18 a.m., Matthew
Knepley wrote:<br>
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<div dir="ltr">On Tue, Nov 26, 2019 at 11:43 AM Danyang Su <<a
href="mailto:danyang.su@gmail.com" moz-do-not-send="true">danyang.su@gmail.com</a>>
wrote:<br>
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<div>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" target="_blank"
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>
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<div>This is not the problem. I believe the problem is that
you are partitioning hybrid cells, and the way we handle</div>
<div>them internally changed, which I think screwed up the
dual mesh for partitioning in your example. I have been</div>
<div>sick, so I have not gotten to your example yet, but I
will.</div>
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<p>Hope you are getting well soon. The mesh is not hybrid, only
prism cells layer by layer. But the height of the prism varies
significantly.</p>
<p>Thanks,</p>
<p>Danyang<br>
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<div> Sorry about that,</div>
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<div> Matt <br>
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<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>
<div><br>
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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>
<div><br>
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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>
<div><br>
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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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<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>
<div><br>
</div>
<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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