<div dir="ltr"><div dir="ltr">On Thu, Nov 28, 2019 at 9:45 PM Swarnava Ghosh <<a href="mailto:swarnava89@gmail.com">swarnava89@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"><div dir="ltr">Hi Barry,<div><br></div><div> "Why do you need a cuboidal domain decomposition?"</div><div><br></div><div>I gave it some thought. I don't always need a cuboidal decomposition. But I would need something that essentially minimized the surface area of the faces of each decomposition. Is there a way to get this? Could you please direct me to a reference a reference where I can read about the domain decomposition strategies used in petsc dmplex. </div></div></blockquote><div><br></div><div>This is the point of graph partitioning, which minimizes the "cut" which the the number of links between one partition and another. The ParMetis</div><div>manual has this kind of information, and citations.</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Sincerely,</div><div>Swarnava</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Nov 25, 2019 at 9:02 PM Smith, Barry F. <<a href="mailto:bsmith@mcs.anl.gov" target="_blank">bsmith@mcs.anl.gov</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
"No, I have an unstructured mesh that increases in resolution away from the center of the cuboid. See Figure: 5 in the ArXiv paper <a href="https://arxiv.org/pdf/1907.02604.pdf" rel="noreferrer" target="_blank">https://arxiv.org/pdf/1907.02604.pdf</a> for a slice through the midplane of the cuboid. Given this type of mesh, will dmplex do a cuboidal domain decomposition?"<br>
<br>
No definitely not. Why do you need a cuboidal domain decomposition? <br>
<br>
Barry<br>
<br>
<br>
> On Nov 25, 2019, at 10:45 PM, Swarnava Ghosh <<a href="mailto:swarnava89@gmail.com" target="_blank">swarnava89@gmail.com</a>> wrote:<br>
> <br>
> Hi Matt,<br>
> <br>
> <br>
> <a href="https://arxiv.org/pdf/1907.02604.pdf" rel="noreferrer" target="_blank">https://arxiv.org/pdf/1907.02604.pdf</a> <br>
> <br>
> On Mon, Nov 25, 2019 at 7:54 PM Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>> wrote:<br>
> 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>
> Dear PETSc users and developers,<br>
> <br>
> I am working with dmplex to distribute a 3D unstructured mesh made of tetrahedrons in a cuboidal domain. I had a few queries:<br>
> 1) Is there any way of ensuring load balancing based on the number of vertices per MPI process.<br>
> <br>
> You can now call DMPlexRebalanceSharedPoints() to try and get better balance of vertices.<br>
> <br>
> Thank you for pointing out this function! <br>
> <br>
> 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. <br>
> <br>
> It sounds like you do not want something that is actually unstructured. Rather, it seems like you want to<br>
> take a DMDA type thing and split it into tets. You can get a cuboidal decomposition of a hex mesh easily.<br>
> Call DMPlexCreateBoxMesh() with one cell for every process, distribute, and then uniformly refine. This<br>
> will not quite work for tets since the mesh partitioner will tend to violate that constraint. You could:<br>
> <br>
> No, I have an unstructured mesh that increases in resolution away from the center of the cuboid. See Figure: 5 in the ArXiv paper <a href="https://arxiv.org/pdf/1907.02604.pdf" rel="noreferrer" target="_blank">https://arxiv.org/pdf/1907.02604.pdf</a> for a slice through the midplane of the cuboid. Given this type of mesh, will dmplex do a cuboidal domain decomposition?<br>
> <br>
> Sincerely,<br>
> SG<br>
> <br>
> a) Prescribe the distribution yourself using the Shell partitioner type<br>
> <br>
> or<br>
> <br>
> b) Write a refiner that turns hexes into tets<br>
> <br>
> We already have a refiner that turns tets into hexes, but we never wrote the other direction because it was not clear<br>
> that it was useful.<br>
> <br>
> Thanks,<br>
> <br>
> Matt<br>
> <br>
> Sincerely,<br>
> SG<br>
> <br>
> <br>
> -- <br>
> 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<br>
> <br>
> <a href="https://www.cse.buffalo.edu/~knepley/" rel="noreferrer" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br>
<br>
</blockquote></div>
</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>