[petsc-users] MWE for DMPlexCreateCGNS

[Andrew Parker]

Will do, I'll get back to you.
Cheers,
Andy

On Tue, 5 Feb 2019 at 19:01, Matthew Knepley <knepley at gmail.com> wrote:

> On Tue, Feb 5, 2019 at 11:13 AM Andrew Parker <andy.john.parker at gmail.com>
> wrote:
>
>> On Tue, 5 Feb 2019 at 15:27, Matthew Knepley <knepley at gmail.com> wrote:
>>
>>> On Tue, Feb 5, 2019 at 9:47 AM Andrew Parker via petsc-users <
>>> petsc-users at mcs.anl.gov> wrote:
>>>
>>>> Does anyone have a MWE for DMPlexCreateCGNS to use in parallel?
>>>> Ideally, read parallel, distribute in parallel, construct ghost cells (for
>>>> parallel comms and halos for physical boundaries)? It's for a cell-centered
>>>> solver working with cgns meshes.  Is there any limitation on cell-types?
>>>>
>>>
>>> 1) CGNS is a terrible format, unfortunately. Are you sure about
>>> committing to it? Always best to question design decisions before lots of
>>> code has been written.
>>>
>>
>>> 2) DMPlexCreateCGNS() probably works, but it has not been tested
>>> exhaustively.
>>>
>>
>>> 3) It does not work in parallel, and is unlikely to in the near future.
>>> In order to read in parallel, you should be able to nicely select
>>>     blocks from disk in the format, and also have local BC specification
>>> (rather than global numbers). MED is a nice format like this.
>>>     It is the CASCADE format, and GMsh uses it internally. We can now
>>> read MED in parallel. Without too much work, we could also
>>>     read ExodusII in parallel I think.
>>>
>>
>> Do you have a MWE for either of those two formats then?
>>
>> Key for me is to be in parallel by the time the setup stage is finished,
>> if there is some serial reading here and there at the initial phase that's
>> fine.  For a cell-centered code I just want to go from file read to
>> parallel distribute, parallel ghost-cell creation, physical halo creation,
>> and boundary condition (faces, edge in 2D) marking re-using as much of the
>> petsc DMPlex system as possible.
>>
>
> Oh, that is fine then.
>
>
>> My main requirement with any file format is the ability in a mesh/cad
>> package to mark complex groups of edges/faces/cells together (on the
>> boundary but also groupings of cells in the volume) to infer groups and
>> therefore bcs, or material regions etc.  I am aware med/exo provide this:
>> my reason for picking cgns is that is central to their format also.  I need
>> to ensure for complex geometry and meshes, that if the file format does
>> encode groupings/bcs then these are accessible after the parallel
>> distribution phase in complete.  It would help me massively if there were
>> an example that does all of this....I'll jump ship on file format to get
>> that.
>>
>
> I think it should be fine to use CGNS for you. How about you make a small
> CGNS file with some marked boundaries
> and I will help get that in as a PETSc example (we can use Plex ex1 to
> read it in and write out the Plex).
>
>   Thanks,
>
>      Matt
>
>
>> Thanks,
>> Andy
>>
>>>
>>> 4) Once read, you get a regular Plex, so you can redistribute, make
>>> ghost cells, etc. as you can for any Plex mesh.
>>>
>>> 5) As long as all you want Plex to do is manage topology and field data,
>>> then you can have whatever mix of cell types you want.
>>>
>>> 6) Limitations on cell types come from routines that calculate geometric
>>> quantities, integrate, etc.
>>>
>>>   Thanks,
>>>
>>>      Matt
>>>
>>
>>
>>>
>>>
>>>> Thanks,
>>>> Andy
>>>>
>>>>
>>>
>>> --
>>> 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/20190205/30e89e64/attachment.html>