[petsc-users] Problem with DMRefine and DMLabel

[Matthew Knepley]

On Wed, Dec 13, 2017 at 7:25 AM, Santos Teixeira Frederico <
fsantost at student.ethz.ch> wrote:

> Hi Matt,
>
> Thanks for your explanation.
>
> The option -dm_refine worked for me because I could keep the effect of -
> dm_plex_separate_marker. I playing with Neumann and Dirichlet boundaries
> to solve the Poiseulle flow, so I need different ids.
>
> The function DMPlexMarkBoundaryFace would set all the points with the same
> id, right?
>

Yes, you are right.

  Thanks,

    Matt


> Regards,
>  Fred.
>
>
> ------------------------------
> *From:* Matthew Knepley [knepley at gmail.com]
> *Sent:* 13 December 2017 12:15
> *To:* Santos Teixeira Frederico
> *Cc:* petsc-users at mcs.anl.gov
> *Subject:* Re: [petsc-users] Problem with DMRefine and DMLabel
>
> On Wed, Dec 13, 2017 at 4:30 AM, Santos Teixeira Frederico <
> fsantost at student.ethz.ch> wrote:
>
>> Hi folks,
>>
>> In the example SNES/62.c, when I use "-simplex 1" and "-refinement_limit
>> 0.05", it seems the refined DMPlex does not carry all the labels from the
>> original DM.
>>
>
> This is correct. Here is the problem. When you use -refinement_limit
> (instead of -dm_refine), I call Triangle/TetGen to do
> the refinement. They do not tell me how they changed the mesh to get
> there, so I have no way of propagating the labels.
> There is a special name ("marker") that I was using for the boundary,
> which I automatically mark after generation.
>
> We could choose to also mark boundary faces, but it seems redundant. If
> you want them marked, you can call
> DMPlexMarkBoundaryFaces() on the new mesh. Does this seem reasonable?
>
>   Thanks,
>
>       Matt
>
>
>> You can see that if you place, in the function CreateMesh, one
>> DMViewFromOptions right after the DMPlexCreateBoxMesh and another
>> DMViewFromOptions after DMRefine. The first output is
>>
>> DM Object: DM_0x84000000_0 1 MPI processes
>>   type: plex
>> DM_0x84000000_0 in 2 dimensions:
>>   0-cells: 9
>>   1-cells: 16
>>   2-cells: 8
>> Labels:
>>   Face Sets: 4 strata with value/size (1 (2), 4 (2), 2 (2), 3 (2))
>>   marker: 4 strata with value/size (4 (5), 1 (3), 2 (5), 3 (3))
>>   depth: 3 strata with value/size (0 (9), 1 (16), 2 (8))
>>
>> which is correct w.r.t. the definition from DMPlexCreateBoxMesh. However,
>> the second output is
>>
>> DM Object: DM_0x84000000_1 1 MPI processes
>>   type: plex
>> DM_0x84000000_1 in 2 dimensions:
>>   0-cells: 145
>>   1-cells: 400
>>   2-cells: 256
>> Labels:
>>   marker: 4 strata with value/size (4 (3), 1 (57), 2 (3), 3 (1))
>>   depth: 3 strata with value/size (0 (145), 1 (400), 2 (256))
>>
>> Note that the label "Face Sets" disappeared and that the label "marker"
>> does not include all the boundary points.
>> The full set of options is:
>>
>> -run_type full
>> -refinement_limit 0.005
>> -simplex 1
>> -dm_view
>> -dm_plex_separate_marker
>> -interpolate 1
>> -vel_petscspace_order 2
>> -pres_petscspace_order 1
>> -ksp_view
>> -ksp_monitor
>> -ksp_type fgmres
>> -ksp_gmres_restart 10
>> -ksp_rtol 1.0e-9
>> -pc_type fieldsplit
>> -pc_fieldsplit_type schur
>> -pc_fieldsplit_schur_factorization_type full
>> -fieldsplit_pressure_ksp_rtol 1e-10
>> -fieldsplit_velocity_ksp_type gmres
>> -fieldsplit_velocity_pc_type lu
>> -fieldsplit_pressure_pc_type jacobi
>> -snes_error_if_not_converged
>> -ksp_error_if_not_converged
>> -snes_view
>> -snes_monitor
>>
>> Am I missing anything?
>>
>> Regards,
>>  Fred.
>>
>
>
>
> --
> 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
>
> https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
>



-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
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