[CIG-SHORT] Linear convergence for nonplanar faults

[Matthew Knepley]

On Wed, Nov 9, 2016 at 9:50 AM, Matthew Knepley <knepley at rice.edu> wrote:

> On Wed, Nov 9, 2016 at 9:42 AM, Josimar Alves da Silva <
> jsilva.mit at gmail.com> wrote:
>
>> Brad,
>>
>> I changed the boundary conditions for Dirichlet BC with constrained
>> displacement perpendicular to the surfaces, but the problem still persists.
>> I am starting to wonder if the nonplanar nature of the fault surface may be
>> causing the problem.
>>
>> The reason for this hypothesis is that I have the same set up but now
>> with flat surfaces, and then in this case I don't find any convergence
>> issue. Everything else was kept the same, except the fault geometry was
>> changed from slightly smoothed (the version I am having problems) to not
>> smoothed.
>>
>
> You NEED to use the exact version of the solver and check for convergence,
> just as in the slides. This will tell us whether your
> formulation is screwed up.
>

I want to follow up here. What i mean is that you need to run with exact
solvers for the two blocks of the
Schur form, and I would test without the custom PC. This is described in
the slides, and also given in the
schur_exact cfg file. Have you been able to run this?

  Thanks,

     Matt


>    Matt
>
>
>> Let me know what you think about this.
>> Thank you
>> Josimar
>>
>>
>>
>>
>> On Wed, Nov 9, 2016 at 10:20 AM, Brad Aagaard <baagaard at usgs.gov> wrote:
>>
>>> On 11/09/2016 07:15 AM, Josimar Alves da Silva wrote:
>>>
>>>> Dear Brad, Matt and Charles,
>>>>
>>>> Thank you again for the suggestions. After reviewing your comments I
>>>> performed the following task in order to solve my problem:
>>>>
>>>> Brad mentioned:
>>>>
>>>>  "1. Without a fault, check convergence with using ML for
>>>> the preconditioned."
>>>>
>>>>          Result: the solver converges fine without the fault and using
>>>> the specified preconditioned.
>>>>
>>>> "2. Add the fault and with zero prescribed slip (FaultCohesiveKin),
>>>> examine the convergence with the solver_fault_fieldsplit.cfg
>>>> parameters."
>>>>
>>>>          Results: no convergence for any solver. Error message:  Linear
>>>> solve did not converge due to DIVERGED_ITS iterations 10000
>>>>
>>>
>>> This suggests there is something wrong with your problem setup. Make
>>> sure you have sufficient Dirichlet BC on each side of the fault to prevent
>>> rigid body motion.
>>>
>>> Brad
>>>
>>>
>>> _______________________________________________
>>> CIG-SHORT mailing list
>>> CIG-SHORT at geodynamics.org
>>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short
>>>
>>
>>
>> _______________________________________________
>> CIG-SHORT mailing list
>> CIG-SHORT at geodynamics.org
>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.geodynamics.org/pipermail/cig-short/attachments/20161110/af2593f6/attachment.html>