<div dir="ltr"><div>SD is a collocation method. Imagine a finite volume method, but instead of a single point (cell and face centers), data is distributed over a grid within the cell and the intersection of the grid with each of the cell's faces. So unlike FV, the communication is for a DIM-1 dimensional grid on the faces. I'll see if the SEM closures help me. <br></div><div><br></div><div><br></div><div><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div><div><div>Thank you.<br>Sincerely,<br>Prateek Gupta, PhD</div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Jul 17, 2022 at 7:59 PM Matthew Knepley <<a href="mailto:knepley@gmail.com">knepley@gmail.com</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"><div dir="ltr"><div dir="ltr">On Sun, Jul 17, 2022 at 7:41 AM Prateek Gupta <<a href="mailto:prateekgupta1709@gmail.com" target="_blank">prateekgupta1709@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"><div>Thanks!<br></div><div>On a similar note, is it possible to define data on faces of a parallel (distributed) dmplex? I have seen the example particular to finite volume methods. But the examples I am building are block-spectral where each element has a higher order polynomial running (much like spectral element methods without the nuisance to separate edge modes and nodal modes). <br></div><div></div></div></blockquote><div><br></div><div>Yes, you can do this. For example, <a href="https://gitlab.com/petsc/petsc/-/blob/main/src/dm/impls/plex/tutorials/ex8.c" target="_blank">https://gitlab.com/petsc/petsc/-/blob/main/src/dm/impls/plex/tutorials/ex8.c</a> shows closures for spectral elements.</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>What I am interested in is, <br></div><div><br></div><div>1. Define face data with multiple DOFs.</div></div></blockquote><div><br></div><div>Yes, faces are mesh points, just like vertices, edges, and cells.</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>2. A quick way of exchanging this face data between processors for calculating fluxes.</div></div></blockquote><div><br></div><div>GlobalToLocal will do this.</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>I have written all of this by hand already. Just wanted to check and compare if dmplex would offer some performance improvement.</div></div></blockquote><div><br></div><div>Possibly. There are some nice optimizations in PetscSF.</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> Additionally, petscFV could be extended to petscSD (SD stands for spectral difference), where finite volume implementation is the zeroth order special case.</div></div></blockquote><div><br></div><div>How is SD different from a spectral element method, with respect to data layout and communication?</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><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div><div><div>Thank you.<br>Sincerely,<br>Prateek Gupta, PhD</div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jul 15, 2022 at 5:43 PM Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</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"><div dir="ltr"><div dir="ltr">On Fri, Jul 15, 2022 at 7:08 AM Prateek Gupta <<a href="mailto:prateekgupta1709@gmail.com" target="_blank">prateekgupta1709@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"><div>Hi,</div><div>Is it possible to generate data using PetscSection with varying degrees of freedom? I am building a sample example on a mixed grid (with both hexahedra and tetrahedra) and thinking if it is possible to generate the face data using PetscSection (or something else) on the resulting. The quad faces have p*p data points and tri faces have p*(p-1)/2 data points.</div></div></blockquote><div><br></div><div>Yes, you can set the size to whatever you want using</div><div><br></div><div> PetscSectionSetDof()</div><div> PetscSectionSetFieldDof()</div><div><br></div><div>The DMPlexCreateSection() routine is overly simplistic here since I assume all k-cells have the same layout.</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><div><div dir="ltr"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div><div><div>Thank you.<br>Sincerely,<br>Prateek Gupta, PhD</div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></blockquote></div>-- <br><div dir="ltr"><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>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr"><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>
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