[petsc-users] Consistent domain decomposition between DMDA and DMPLEX

[Swarnava Ghosh]

Hi Mark and Matt,

I calculate my unknown fields at the nodes of my coarse unstructured mesh,
and then project the solution at some of the fine structured mesh nodes.
The only global matrix I form is on the unstructured coarse mesh to do a
Poisson solve.

Sincerely,
Swarnava

On Thu, Mar 28, 2019 at 5:56 AM Mark Adams <mfadams at lbl.gov> wrote:

>
>>
>> That seems like a bad tradeoff. You avoid one communication during
>> injection for at least that much or more during
>> FE assembly on that cell partition?
>>
>>
> I am just guessing about the purpose as a way to describing what they are
> asking for.
>
>
>>   Matt
>>
>>
>>>
>>>>   Thanks,
>>>>
>>>>     Matt
>>>>
>>>>
>>>>> Sincerely,
>>>>> Swarnava
>>>>>
>>>>> On Fri, Mar 22, 2019 at 4:08 PM Mark Adams <mfadams at lbl.gov> wrote:
>>>>>
>>>>>> Matt,
>>>>>> I think they want a vertex partitioning. They may have elements on
>>>>>> the unstructured mesh that intersect with any number of processor domains
>>>>>> on the structured mesh. But the unstructured mesh vertices are in the
>>>>>> structured mesh set of vertices. They want the partition of the
>>>>>> unstructured mesh vertices (ie, matrices) to be slaved to the partitioning
>>>>>> of the structured mesh.
>>>>>> Do I have that right Swarnava?
>>>>>> Mark
>>>>>>
>>>>>> On Fri, Mar 22, 2019 at 6:56 PM Matthew Knepley via petsc-users <
>>>>>> petsc-users at mcs.anl.gov> wrote:
>>>>>>
>>>>>>> On Thu, Mar 21, 2019 at 8:20 PM Swarnava Ghosh via petsc-users <
>>>>>>> petsc-users at mcs.anl.gov> wrote:
>>>>>>>
>>>>>>>> Dear PETSc users and developers,
>>>>>>>>
>>>>>>>> I am new to DMPLEX and had a query regarding setting up a
>>>>>>>> consistent domain decomposition of two meshes in PETSc.
>>>>>>>> I have a structured finite difference grid, managed through DMDA. I
>>>>>>>> have another unstructured finite element mesh managed through DMPLEX. Now
>>>>>>>> all the nodes in the unstructured finite element mesh also belong to the
>>>>>>>> set of nodes in the structured finite difference mesh (but not necessarily
>>>>>>>> vice-versa), and the number of nodes in DMPLEX mesh is less than the number
>>>>>>>> of nodes in DMDA mesh. How can I guarantee a consistent domain
>>>>>>>> decomposition of the two meshes? By consistent, I mean that if a process
>>>>>>>> has a set of nodes P from DMDA, and the same process has the set of nodes Q
>>>>>>>> from DMPLEX, then Q is a subset of P.
>>>>>>>>
>>>>>>>
>>>>>>> Okay, this is not hard. DMPlexDistribute() basically distributes
>>>>>>> according to a cell partition. You can use PetscPartitionerShell() to stick
>>>>>>> in whatever cell partition you want. You can see me doing this here:
>>>>>>>
>>>>>>>
>>>>>>> https://bitbucket.org/petsc/petsc/src/e2aefa968a094f48dc384fffc7d599a60aeeb591/src/dm/impls/plex/examples/tests/ex1.c#lines-261
>>>>>>>
>>>>>>> Will that work for you?
>>>>>>>
>>>>>>>   Thanks,
>>>>>>>
>>>>>>>     Matt
>>>>>>>
>>>>>>>
>>>>>>>> I look forward to your response.
>>>>>>>>
>>>>>>>> Sincerely,
>>>>>>>> Swarnava
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> 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.cse.buffalo.edu/~knepley/>
>>>>>>>
>>>>>>
>>>>
>>>> --
>>>> 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.cse.buffalo.edu/~knepley/>
>>>>
>>>
>>
>> --
>> 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.cse.buffalo.edu/~knepley/>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20190328/0a951d46/attachment.html>