<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Scott,<div><br></div><div>Are you using linear interpolation for your initial stresses?</div><div><br></div><div>Charles</div><div><br></div><div><br><div><div>On 12/11/2012, at 4:43 PM, Scott Henderson wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Brad,<br><br>If I understand you correctly, I should bring the tolerances closer together, so instead of:<br>ksp_rtol = 1.0e-10<br>ksp_atol = 1.0e-20<br><br>I've tried (among other combinations):<br>ksp_rtol = 1.0e-18<br>ksp_atol = 1.0e-20<br>ksp_max_it = 200<br><br>And I always converge to the same result (-0.017m surface subsidence).<br><br>Could this have something to do with the way the initial_stresses are getting assigned? Basically, I'm thinking that if the bottom elements are getting initial stresses slightly less than lithostatic there would be subsidence of the domain. For the heck of it I tried specifying the max stress at 99km instead of 100km. I thought this would result in an error, but Pylith runs to completion, and the displacements turn out to be +17m. <br><br>Thanks,<br>Scott<br><br><br><br>On Nov 11, 2012, at 7:41 PM, Brad Aagaard <<a href="mailto:baagaard@usgs.gov">baagaard@usgs.gov</a>> wrote:<br><br><blockquote type="cite">Scott,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">There are a couple of issues to consider:<br></blockquote><blockquote type="cite">(1) If you have nonuniform density, then the initial stresses as a <br></blockquote><blockquote type="cite">function of depth are more complicated than a constant linear increase <br></blockquote><blockquote type="cite">with depth. You need to calculate the lithostatic stress as a function <br></blockquote><blockquote type="cite">of depth and use that for the initial stresses.<br></blockquote><blockquote type="cite">(2) Tighten the convergence tolerance (ksp_rtol and ksp_atol) to get a <br></blockquote><blockquote type="cite">more accurate solution.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Regards,<br></blockquote><blockquote type="cite">Brad<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">On 11/11/12 4:25 PM, Scott Henderson wrote:<br></blockquote><blockquote type="cite"><blockquote type="cite">Hello,<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">I've been modifying the step16.cfg tutorial for a larger mesh. If I<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">increase the domain size from 6x6x4 to 200x200x100km, and change the<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">initial_stress.spatialdb to correspond to the new lithostatic stress<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">at the base of the mesh (-2451637500Pa). I'm finding that the elastic<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">solution has ~2 cm of subsidence at the surface, but I expect zero<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">displacement. This appears to be independent of element size.<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Also, if I have non-uniform density in the mesh (for example an<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">embedded weak layer or arbitrary shape), how might I set up the<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">initial stresses to compensate for gravity? I'm guessing that the<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">only way to go about this is run the solution without initial<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">stresses, extract the stress values at a few points through each<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">material, then set up separate spatial databases for each material<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">for the next run?<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Thanks, Scott<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">step16_1 = same settings as step16, but larger mesh step16_2 = just<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">elastic solution<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">_______________________________________________ CIG-SHORT mailing<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">list <a href="mailto:CIG-SHORT@geodynamics.org">CIG-SHORT@geodynamics.org</a><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><a href="http://geodynamics.org/cgi-bin/mailman/listinfo/cig-short">http://geodynamics.org/cgi-bin/mailman/listinfo/cig-short</a><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">_______________________________________________<br></blockquote><blockquote type="cite">CIG-SHORT mailing list<br></blockquote><blockquote type="cite"><a href="mailto:CIG-SHORT@geodynamics.org">CIG-SHORT@geodynamics.org</a><br></blockquote><blockquote type="cite"><a href="http://geodynamics.org/cgi-bin/mailman/listinfo/cig-short">http://geodynamics.org/cgi-bin/mailman/listinfo/cig-short</a><br></blockquote><br>_______________________________________________<br>CIG-SHORT mailing list<br><a href="mailto:CIG-SHORT@geodynamics.org">CIG-SHORT@geodynamics.org</a><br>http://geodynamics.org/cgi-bin/mailman/listinfo/cig-short<br></div></blockquote></div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Charles A. Williams</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Scientist<br>GNS Science<br>1 Fairway Drive, Avalon<br>PO Box 30368<br>Lower Hutt 5040<br>New Zealand<br>ph (office): 0064-4570-4566<br>fax (office): 0064-4570-4600</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:C.Williams@gns.cri.nz">C.Williams@gns.cri.nz</a></div></div></div></span></span>
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