On 2019-11-26 10:18 a.m., Matthew Knepley wrote:
On Tue, Nov 26, 2019 at 11:43 AM Danyang Su <[email protected]
<mailto:[email protected]>> wrote:
On 2019-11-25 7:54 p.m., Matthew Knepley wrote:
On Mon, Nov 25, 2019 at 6:25 PM Swarnava Ghosh
<[email protected] <mailto:[email protected]>> wrote:
Dear PETSc users and developers,
I am working with dmplex to distribute a 3D unstructured mesh
made of tetrahedrons in a cuboidal domain. I had a few queries:
1) Is there any way of ensuring load balancing based on the
number of vertices per MPI process.
You can now call DMPlexRebalanceSharedPoints() to try and get
better balance of vertices.
Hi Matt,
I just want to follow up if this new function can help to solve
the "Strange Partition in PETSc 3.11" problem I mentioned before.
Would you please let me know when shall I call this function?
Right before DMPlexDistribute?
This is not the problem. I believe the problem is that you are
partitioning hybrid cells, and the way we handle
them internally changed, which I think screwed up the dual mesh for
partitioning in your example. I have been
sick, so I have not gotten to your example yet, but I will.
Hope you are getting well soon. The mesh is not hybrid, only prism cells
layer by layer. But the height of the prism varies significantly.
Thanks,
Danyang
Sorry about that,
Matt
call DMPlexCreateFromCellList
call DMPlexGetPartitioner
call PetscPartitionerSetFromOptions
call DMPlexDistribute
Thanks,
Danyang
2) As the global domain is cuboidal, is the resulting domain
decomposition also cuboidal on every MPI process? If not, is
there a way to ensure this? For example in DMDA, the default
domain decomposition for a cuboidal domain is cuboidal.
It sounds like you do not want something that is actually
unstructured. Rather, it seems like you want to
take a DMDA type thing and split it into tets. You can get a
cuboidal decomposition of a hex mesh easily.
Call DMPlexCreateBoxMesh() with one cell for every process,
distribute, and then uniformly refine. This
will not quite work for tets since the mesh partitioner will tend
to violate that constraint. You could:
a) Prescribe the distribution yourself using the Shell
partitioner type
or
b) Write a refiner that turns hexes into tets
We already have a refiner that turns tets into hexes, but we
never wrote the other direction because it was not clear
that it was useful.
Thanks,
Matt
Sincerely,
SG
--
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/>
