[aspect-devel] problem with ASPECT - the iterative Stokes solver did not converge

[Wolfgang Bangerth]

Petar,
let me pull this discussion to the mailing list since the authors of the 
Steinberger model are there.


> I have experienced a problem running ASPECT. It seems that the iterative
> Stokes solver did not converge after three days of the job running on 48
> CPUs - please see attached log files (/aspect.e2477653, aspect.o2477653
> & log.txt/).

This is almost certainly an unrelated observation, but with as few 
unknowns as you have, you should first run small models using only a 
single processor when you try things out.

My rule of thumb is that you can run models with a few 100,000 unknowns 
on a single processor. For parallel computations, you typically don't 
gain anything if you have fewer than 50,000 unknowns per processor -- 
i.e., in your case, 4 or 5 processors is about the optimum.

> However, my goal is to use the depth-dependent (i.e., radial) viscosity
> profile (Mitrovica & Forte, 2004; please see attached file:
> /mitro-forte-2004-radial-visc-new.txt/) jointly with lateral variations
> in viscosity (see below /shell_simple_3d_new.prm/). For example, to use
> something similar to the Steinberger model:
> subsection Material model
>      set Model name = Steinberger
>      subsection Steinberger model
>          set Bilinear interpolation = true
>          set Compressible = true

What happens if you set this to false?

I don't know the parameters to the Steinberger model, so can't comment 
on their validity. I hope someone else on the mailing list may be able 
to provide more feedback.

Best
   Wolfgang
-- 
------------------------------------------------------------------------
Wolfgang Bangerth               email:            bangerth at math.tamu.edu
                                 www: http://www.math.tamu.edu/~bangerth/