[MOAB-dev] periodic boundaries

[Vijay S. Mahadevan]

Alex, I don't think we have the necessary semantics to express
periodic boundaries natively on an unstructured mesh in MOAB. Partly
because, no one asked for it.

So couple of questions for you.

1) Serial or parallel runs ?
a) Serial is relatively much simpler and you can get away with MOAB
implementation as it stands.
b) Parallel complicates this since the elements on either side of a
periodic boundary will be on different partitions and we need to
modify shared entity resolution to let it know which process to send
messages.

2) Boundary description: nodes vs surfaces (edges)
a) In serial, it could be as simple as matching nodes with the same
tag value or say Y-coordinate during your setup phase and using that
information later during computation
b) In parallel, again, you need to rely on resolve_shared_ents to work
correctly so that things work out of the box.

3) Do you need adjacency queries ?

4) In parallel, do you expect ghost layers on the periodic boundary ?

Depending on what your use case is, this could be done in a variety of
ways. Let us know.

Vijay

On Wed, Mar 2, 2016 at 11:29 AM, Alexander Nikolas Breuer
<anbreuer at ucsd.edu> wrote:
> Writing about nodes:
>
> I am searching the neighbors by going from triangles over edges to
> neighboring triangles again. Let me know if it's worth trying to go through
> the vertices for the boundary.
>
> Thanks,
>
> Alex
>
> Sent from my iPhone
>
> On Mar 2, 2016, at 9:20 AM, Alexander Nikolas Breuer <anbreuer at ucsd.edu>
> wrote:
>
> Uh, ok. Here's a link:
> https://www.dropbox.com/s/f41mmkl47zxrm0a/gmsh.msh?dl=0
>
> The bnd condition is described in terms of nodes:
>
> $Periodic
> 3
> 0 2 1
> 1
> 2 1
> 0 3 4
> 1
> 3 4
> 1 2 4
> 9
> 14 40
> 15 39
> 16 38
> 17 37
> 18 36
> 19 35
> 20 34
> 21 33
> 22 32
> $EndPeriodic
>
> Alex
>
> Sent from my iPhone
>
> On Mar 2, 2016, at 6:19 AM, Grindeanu, Iulian R. <iulian at mcs.anl.gov> wrote:
>
> attachment was scrubbed, can you send it again ? maybe as a zip file?
> somehow,  it does not like msh suffix
> Thanks,
> Iulian
> ________________________________
> From: moab-dev-bounces at mcs.anl.gov [moab-dev-bounces at mcs.anl.gov] on behalf
> of Alexander Nikolas Breuer [anbreuer at ucsd.edu]
> Sent: Tuesday, March 01, 2016 11:20 PM
> To: moab-dev at mcs.anl.gov
> Subject: [MOAB-dev] periodic boundaries
>
> Dear MOAB-team,
>
> I am trying to read a triangular mesh with periodic boundaries created by
> gmsh into MOAB (attached). However I don’t see this when going through
> MOAB’s adjacencies. Is there a way to make the mesh reader aware of periodic
> boundaries?
>
> Thanks,
>
> Alex
>
>
>
> --
> Alexander Breuer
> University of California, San Diego
> San Diego Supercomputer Center
> 9500 Gilman Drive MC 0505
> La Jolla, California 92093-0505, USA
> http://hpgeoc.sdsc.edu
> +1 (858) 822-5692
>
>
>