[CIG-SHORT] Pylith dies after thousands of time steps (convergence issue)

[Brad Aagaard]

Tabrez-

You may want to set ksp_monitor=true so that you can see the residual. If the 
residual increases significantly, the solution is losing convergence. This 
can be alleviated a bit by using an absolute convergence tolerance 
(ksp_atol). You probably need a slightly smaller time step or slightly higher 
quality mesh (improve the aspect ratio of the most distorted cells).

Brad


On Wednesday 29 April 2009 1:13:21 pm Tabrez Ali wrote:
> Brad
>
> I think you were right. The elastic problem worked out fine. I will
> now try to play with time step (for the viscous runs)
>
> Tabrez
>
> On Apr 29, 2009, at 1:19 PM, Brad Aagaard wrote:
> > On Wednesday 29 April 2009 10:09:26 am Tabrez Ali wrote:
> >> Also I dont see the error until ~9000 time steps with one set of
> >> material properties but get the error at around 4000th time step with
> >> a different set of material properties (on the same mesh).
> >
> > This seems to indicate a time-integration stability issue. Does the
> > one that
> > has an error after 4000 time steps have a smaller Maxwell time? You
> > might try
> > running with purely elastic properties. If that works, then you may
> > need to
> > reduce your time step.