<div class="gmail_quote">On Thu, Dec 22, 2011 at 19:20, Mohamad M. Nasr-Azadani <span dir="ltr"><<a href="mailto:mmnasr@gmail.com">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>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">http://www.mcs.anl.gov/petsc/documentation/faq.html#kspdiverged</a></div>
<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>That was about solving the coupled system. That shouldn't be an issue for the Poisson problem.</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><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>