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

[Matthew Knepley]

On Tue, Oct 28, 2014 at 12:05 PM, Tabrez Ali <stali at geology.wisc.edu> wrote:

>  Matt
>
> The analytical (Okada) solution is wrong at the fault. PETSc is right. It
> is a strike slip fault and constraints are being enforced correctly.
>

If the solution is right and the residual is large, then the function
calculating the residual is wrong, since
the residual is supposed to define the solution.

   Matt


>
> Tabrez
>
>
>
> On 10/28/2014 11:57 AM, Matthew Knepley wrote:
>
>  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
>
>
>


-- 
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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