Dear Matt,
Thanks for your quick response.
I have a DMPlex with a polyhedral mesh, and have defined a number of vectors with data at the cell center. I have generated data
for a number of timesteps, and I write the data for each point to a file together with the (x,y,z) co-ordinate of the cell center.
When I want to do a restart from the DMPlex, I recreate the DMplex with the polyhedral mesh, redistribute it, and for each cell
center find the corresponding (x,y,z) co-ordinate and insert the data that corresponds to it. This is quite expensive, as it
means I need to compare doubles very often.
But reading your response, this may not be a bad way of doing it?
Thanks,
Berend.
On 1/22/24 18:58, Matthew Knepley wrote:
On Mon, Jan 22, 2024 at 10:49 AM Berend van Wachem <[email protected]
<mailto:[email protected]>> wrote:
Dear Petsc-Team,
Is there a good way to define a unique integer number in each element
(e.g. a cell) of a DMPlex mesh, which is in the same location,
regardless of the number of processors or the distribution of the mesh
over the processors?
So, for instance, if I have a DMPlex box mesh, the top-right-front
corner element (e.g. cell) will always have the same unique number,
regardless of the number of processors the mesh is distributed over?
I want to be able to link the results I have achieved with a mesh from
DMPlex on a certain number of cores to the same mesh from a DMPlex on a
different number of cores.
Of course, I could make a tree based on the distance of each element to
a certain point (based on the X,Y,Z co-ordinates of the element), and go
through this tree in the same way and define an integer based on this,
but that seems rather cumbersome.
I think this is harder than it sounds. The distance will not work because it
can be very degenerate.
You could lexicographically sort the coordinates, but this is hard in parallel.
It is fine if you are willing
to gather everything on one process. You could put down a p4est, use the Morton order to number them since this is stable for a
given refinement. And then within each box lexicographically sort the centroids. This is definitely cumbersome, but I cannot
think of anything else. This also might have parallel problems since you need to know how much overlap you need to fill each box.
Thanks,
Matt
Thanks and best regards, Berend.
--
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/>
