<div dir="ltr"><div dir="ltr">On Tue, Nov 26, 2019 at 11:43 AM Danyang Su <<a href="mailto:danyang.su@gmail.com">danyang.su@gmail.com</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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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">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></div></blockquote><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><div><br></div><div> Sorry about that,</div><div><br></div><div> Matt <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div bgcolor="#FFFFFF">
<p>call DMPlexCreateFromCellList<br>
<br>
call DMPlexGetPartitioner<br>
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call PetscPartitionerSetFromOptions<br>
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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>
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<div> a) Prescribe the distribution yourself using the Shell
partitioner type</div>
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<div>or</div>
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<div> b) Write a refiner that turns hexes into tets</div>
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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>
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<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">https://www.cse.buffalo.edu/~knepley/</a><br>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><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">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>