On Thu, Dec 22, 2011 at 7:37 PM, Mohamad M. Nasr-Azadani <span dir="ltr"><<a href="mailto:mmnasr@gmail.com">mmnasr@gmail.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Thanks so much Jed for your prompt response. I will start experimenting with all the suggestions. </blockquote><div><br></div><div>dtol failure is impossible for GMRES (and CG). Consider checking with that.</div><div><br>
</div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Best, </div><div>Mohamad</div><div><br><br><div class="gmail_quote">On Thu, Dec 22, 2011 at 5:31 PM, Jed Brown <span dir="ltr"><<a href="mailto:jedbrown@mcs.anl.gov" target="_blank">jedbrown@mcs.anl.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="gmail_quote"><div>On Thu, Dec 22, 2011 at 19:20, Mohamad M. Nasr-Azadani <span dir="ltr"><<a href="mailto:mmnasr@gmail.com" target="_blank">mmnasr@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Any hints on what is happening here or how I could narrow it down?</blockquote><div><br></div></div><div>I would start by following the general advice in the FAQ</div><div><br></div><div><a href="http://www.mcs.anl.gov/petsc/documentation/faq.html#kspdiverged" target="_blank">http://www.mcs.anl.gov/petsc/documentation/faq.html#kspdiverged</a></div>
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<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> I know that we had an early discussion on the convergnce for the incompressible CFD problems and boomerAMG preconditioning,</blockquote>
<div><br></div></div><div>That was about solving the coupled system. That shouldn't be an issue for the Poisson problem.</div><div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
but it seems that for this case, that is the only one that does not blow up for most of the time integration I have. </blockquote></div></div><br><div>Since this problem only occurs after long time integration, you might consider writing out the model state when you see divergence so that you can experiment with alternative methods quickly.</div>
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</blockquote></div><br><br clear="all"><div><br></div>-- <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>