[petsc-users] Fieldsplit with LSC for constrained elasticity/poroelasticity?

[Matthew Knepley]

On Tue, Oct 28, 2014 at 11:56 AM, Tabrez Ali <stali at geology.wisc.edu> wrote:

> Jed
>
> You're right and it is precisely what I am trying to understand as well. I
> am attaching the comparison to the analytical solution. As you can see the
> agreement is almost perfect, except at the discontinuity (y=0 in the
> analytical solution).
>
> So why am I getting the correct solution when according to true residuals
> I should not?


The discontinuty is generating the large residuals. Your saddle is not
actually enforcing
the discontinuty, so you get the bulk mostly right by solving the (1,1)
block, but not
the slip. At least it looks that way to me.

   Matt


>
> Tabrez
>
>
> On 10/28/2014 11:18 AM, Jed Brown wrote:
>
>> Tabrez Ali <stali at geology.wisc.edu> writes:
>>
>>  Matt and Jed
>>>
>>> But it does appear to work well in practice (as in I get the correct
>>> solution).
>>>
>> Your "correct" solution has a residual seven orders of magnitude bigger
>> than the initial guess.  Does that not give you pause?
>>
>
>


-- 
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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