hi
A couple of years back I was asking questions here about implementing
"dual porosity" finite volume methods via PETSc (in which flow in
fractured media is represented by adding extra "matrix" cells nested
inside the original mesh cells).
At the time I was asking about how to solve the resulting linear
equations more efficiently (I still haven't worked on that part of it
yet, so at present it's still just using a naive linear solve which
doesn't take advantage of the particular sparsity pattern), and about
how to add the extra cells into the DMPlex mesh, which I figured out how
to do.
It is working OK except that strong scaling performance is not very
good, if dual porosity is applied over only part of the mesh. I think
the reason is that I read the mesh in and distribute it, then add the
dual porosity cells in parallel on each process. So some processes can
end up with more cells than others, in which case the load balancing is bad.
I'm considering trying to change it so that I add the dual porosity
cells to the DMPlex in serial, before distribution, to regain decent
load balancing.
To do that, I'd also need to compute the cell centroids in serial (as
they are often used to identify which cells should have dual porosity
applied), using DMPlexComputeGeometryFVM(). The geometry vectors would
then have to be distributed later, I guess using something like
DMPlexDistributeField().
Should I expect a significant performance hit from calling
DMPlexComputeGeometryFVM() on the serial mesh compared with doing it (as
now) on the distributed mesh? It will increase the serial fraction of
the code but as it's only done once at the start I'm hoping the benefits
will outweigh the costs.
- Adrian
--
Dr Adrian Croucher
Senior Research Fellow
Department of Engineering Science
University of Auckland, New Zealand
email:[email protected]
tel: +64 (0)9 923 4611
