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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi Matt,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I intend to perform a scaling study – I have a few more questions from ex56<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><b><span style="font-size:10.0pt;font-family:"Courier New";color:black">3D, tri-quadratic hexahedra (Q1), displacement finite element formulation.<o:p></o:p></span></b></p>
<p class="MsoListParagraph" style="margin-left:54.0pt;text-indent:-36.0pt;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-fareast-language:EN-US"><span style="mso-list:Ignore">i)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="mso-fareast-language:EN-US">What makes the problem non-linear? I believe SNES are used to solve non-linear problems.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:54.0pt;text-indent:-36.0pt;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-fareast-language:EN-US"><span style="mso-list:Ignore">ii)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="mso-fareast-language:EN-US">2,2,1 does it present the number of elements used in each direction?<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:54.0pt;text-indent:-36.0pt;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-fareast-language:EN-US"><span style="mso-list:Ignore">iii)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="mso-fareast-language:EN-US">What makes the problem unstructured? I believe the geometry is a cube or cuboid – is it because it uses DMPlex?
<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:54.0pt;text-indent:-36.0pt;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-fareast-language:EN-US"><span style="mso-list:Ignore">iv)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="mso-fareast-language:EN-US">Do any external FEM package with an unstructured problem domain has to use DMPlex mat type?
<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:54.0pt;text-indent:-36.0pt;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="mso-fareast-language:EN-US"><span style="mso-list:Ignore">v)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="mso-fareast-language:EN-US">What about -mat_type (not _dm_mat_type) ajicusparse – will it work with unstructured FEM discretised domains?<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I tried to run two problems of ex56 with two different domain size ( - attached you find the log_view outputs of both on<u>
</u><b>gpus</b>) using _pc_type asm:<b><o:p></o:p></b></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="p1"><span class="s1"><span style="font-size:10.0pt">./ex56 -cells 2,2,1 -max_conv_its 2 -lx 1. -alpha .01 -petscspace_degree 1 -ksp_type cg -ksp_monitor -ksp_rtol 1.e-8 -pc_type asm -snes_monitor -use_mat_nearnullspace true</span></span><span class="apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="s1"><span style="font-size:10.0pt">-snes_rtol 1.e-10 > output_221.txt<o:p></o:p></span></span></p>
<p class="p1"><span class="s1"><span style="font-size:10.0pt"><o:p> </o:p></span></span></p>
<p class="p1"><span style="font-size:10.0pt"><o:p> </o:p></span></p>
<p class="p1"><span class="s1"><span style="font-size:10.0pt">./ex56 -cells 10,10,5 -max_conv_its 2 -lx 1. -alpha .01 -petscspace_degree 1 -ksp_type cg -ksp_monitor -ksp_rtol 1.e-8 -pc_type asm -snes_monitor -use_mat_nearnullspace true</span></span><span class="apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="s1"><span style="font-size:10.0pt">-snes_rtol 1.e-10 > output_221.txt<o:p></o:p></span></span></p>
<p class="p1"><span class="s1"><span style="font-size:10.0pt"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Below is the SNES iteration for problem with 2,2,1 cells which converges after two non-linear iterations:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">0 SNES Function norm 0.000000000000e+00
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 0 SNES Function norm 7.529825940191e+01<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 1 SNES Function norm 4.734810707002e-08<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 2 SNES Function norm 1.382827243108e-14<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Below is the SNES iteration for problem with 10,10,5 cells– why does it first decrease and then increase to
<b>0 SNES Function norm 1.085975028558e+01</b> and finally converge?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 0 SNES Function norm 2.892801019593e+01<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 1 SNES Function norm 5.361683383932e-07
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 2 SNES Function norm 1.726814199132e-14
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 0 SNES Function norm 1.085975028558e+01<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 1 SNES Function norm 2.294074693590e-07<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"> 2 SNES Function norm 2.491900236077e-14<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Karthik.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Matthew Knepley <knepley@gmail.com><br>
<b>Date: </b>Thursday, 2 December 2021 at 10:57<br>
<b>To: </b>"Chockalingam, Karthikeyan (STFC,DL,HC)" <karthikeyan.chockalingam@stfc.ac.uk><br>
<b>Cc: </b>"petsc-users@mcs.anl.gov" <petsc-users@mcs.anl.gov><br>
<b>Subject: </b>Re: [petsc-users] Unstructured mesh<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, Dec 2, 2021 at 3:33 AM Karthikeyan Chockalingam - STFC UKRI <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk">karthikeyan.chockalingam@stfc.ac.uk</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hello,</p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> </p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Are there example tutorials on unstructured mesh in ksp? Can some of them run on gpus?</p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">There are many unstructured grid examples, e.g. SNES ex13, ex17, ex56. The solver can run on the GPU, but the vector/matrix<o:p></o:p></p>
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<p class="MsoNormal">FEM assembly does not. I am working on that now.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> Thanks,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> Matt<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Kind regards,</p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Karthik.</p>
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<p class="MsoNormal"><br clear="all">
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">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<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><o:p></o:p></p>
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