[petsc-users] DIVERGED_NANORINF for CG/Bjacobi for transient diffusion

[Matthew Knepley]

On Wed, Mar 30, 2016 at 4:18 PM, Justin Chang <jychang48 at gmail.com> wrote:

> Hi all,
>
> I am getting this error:
>
> Linear solve did not converge due to DIVERGED_NANORINF
>
> when solving an FEM for transient diffusion using hexahedron elements. The
> problem is highly heterogeneous (i.e., dispersion tensor with varying
> cell-centered velocity) and normally CG/Bjacobi has done well for me. If I
> did CG/Jacobi, my solver would require nearly 7000 iterations, but would
> get the "expected" solution.
>
> What does the above error mean? And what could I do to address it?
>

Almost certainly ILU craps out. Try using LU as the subsolver instead.

  Matt


> Thanks,
> Justin
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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