[petsc-users] Command lines to reproduce the tests of "Composing scalable nonlinear algebraic solvers"

[Matthew Knepley]

On Thu, Aug 25, 2016 at 8:46 AM, Karin&NiKo <niko.karin at gmail.com> wrote:

> Dear PETSc gurus,
>
> Thanks to the help of Matthew, I have been able to reproduce in PETSc some
> tests of the paper of Peter Brune et al. entitled "Composing scalable
> nonlinear algebraic solvers", with special attention to the elasticity test.
> I have also tried to reproduce it in a widely used mechanics finite
> element solver and I cannot obtain the same results, mainly because of my
> lack of undestanding of the boundary conditions and of the loading.
>
> According to the paper, I undestand that the edges in red in the attached
> image are fully clamped. If I do that, I do observe a rotation of the grey
>  face (see attached image).
>
> If I clamp the over-mentioned edges plus I forbid the normal displacement
> of the grey face, I get a quite similar warped shape but the details of the
> deformation near the clamped faces are very different
>
> In the paper, the loading is defined as a volume force applied to the
> whole structure whereas in Wriggers' book, it is defined as a nodal force.
>
> Could you please give me some details on these points?
>

I am looking at the code:

https://bitbucket.org/petsc/petsc/src/bd8b9ddea6dc39522a77cdc0585cbede38eb66bb/src/snes/examples/tutorials/ex16.c?at=master&fileviewer=file-view-default#ex16.c-204

and to me it clearly looks like we are fixing just the top edge on each
side. I do not see anything forcing the end faces to
stay aligned with the y-z plane, but maybe I am missing something. Can you
just compare the residual/Jacobian for the
initial guess?

   Matt


> Best regards,
> Nicolas
>
> 2016-08-23 20:25 GMT+02:00 Matthew Knepley <knepley at gmail.com>:
>
>> On Tue, Aug 23, 2016 at 10:54 AM, Karin&NiKo <niko.karin at gmail.com>
>> wrote:
>>
>>> Dear PETSc team,
>>>
>>> I have read with high interest the paper of Peter Brune et al. entitled
>>> "Composing scalable nonlinear algebraic solvers".
>>> Nevertheless I would like to be able to reproduce the tests that are
>>> presented within (mainly the elasticity problem, ex16).
>>>
>>> Could you please provide us with the command lines of these tests?
>>>
>>
>> I believe Peter used the attached script.
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Best regards,
>>> Nicolas
>>>
>>
>>
>>
>> --
>> 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
>>
>
>


-- 
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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