hi Matt,
On 14/06/21 9:54 pm, Matthew Knepley wrote:
Okay, I think it is not so hard to get what you want in parallel.
There are only two kinds of faces with supportSize == 1:
a) Faces on the global boundary
b) Faces which are "shared"
I think there is an unfortunate corner case in which faces can be both
on the global boundary *and* shared.
For example: consider a square 2D mesh which is partitioned down the
middle, so one process has the left half. With overlap = 1, a row of
ghost cells will be added along the right-hand edge of this half of the
mesh. The two faces at top and bottom of this row of ghost cells are on
the global boundary and also shared.
With your algorithm these would be labelled as flux faces, but they
shouldn't be (as they are on the global boundary). I can't see a way to
eliminate those kinds of shared faces - can you?
- Adrian
It is the second set that is somewhat confusing because PetscSF does
not have 2-sided information by default. However, it can make it.
There is a two-step check for "shared":
1) Is the face in the PetscSF? Here you just check for it in the
sorted "locals" array from PetscSFGetGraph()
2) Is the face ghosted on another process? You can get this from
PetscSFGetRootRanks().
I just wrote a small function to check for "shared" points. After
that, I think you can just run
1) After distribution, loop overall faces on current process
If face on open boundary, label face as flux face
else:
if face has supportSize != 1 or (supportSize == 1 && shared),
label face as flux face
Thanks,
Matt
--
Dr Adrian Croucher
Senior Research Fellow
Department of Engineering Science
University of Auckland, New Zealand
email: [email protected]
tel: +64 (0)9 923 4611
