[Trilinos-Users] IO and general questions

[Carlos Breviglieri]

Hello, I am Carlos, a PhD candidate in Brazil. I've been recently checking
out Trilinos as a basis for a CFD application. My research focus is on
high-order unstructured methods for aeronautical/space applications. I have
checked the TUG videos and must say that its a great way to get started.
I've done most of the tutorials and read some doxygen stuff.

I've come across a couple of points with some packages that I hope someone
can clarify. These are somewhat entrypoint questions for me and, hopefully,
might be usefull to someone else get started. I am using git sources from
august 13th. I apologize if this is not the proper mail-list to do so and
the lengthy topic...

*SEACAS::Ioss*
I need to do parallel IO. I've got experience with the CGNS/HDF5 library
and I am aware of the par_exo factory (Iopx) for the exodus format and got
it compiled with specific flags from cmake. I can switch to exodus but I
was not able to confirm, from the source code, that:

a) can it do parallel read/write + parallel decomposition? From
"packages/seacas/libraries/ioss/src/main/io_shell.C" it is possible to
partition (zoltan or metis) the domain but I believe that at one moment one
proc will hold the entire mesh, before calling the partitioner interface.
Afterwards, it can compose the output, which is a feature I am interested
in. Moreover the source states that, at this point, no parallel RESTART is
supported.

So, the questions here are:
a.1) Is Iopx able to do parallel IO (I assume so since it uses the netcdf4
format)?

a.2) Is Zoltan (did not check Zoltan2) able to do parallel decomposition
internally (not rely on ParMETIS)?

a.3) Are composition methods (join the output solution files) experimental?
(had issues with netcdf library versioning)

*STK
*
b) I was able to read and decompose an exodus/netcdf4 mesh (through
meshData.properties) in Panzer using exodus stk_interface class, but I am
not sure if the decomposition and IO happens in parallel...?

c) I have not found any indication from stk sources that it supports output
composition... Can it be done? It uses internal write routines that act
upon an Ioss database, which does support it. I have also checked the
tExodusReaderFactory.cpp from Panzer package that interfaces with STK but
such functionality was not present.

d) Is STK able to do AMRC (Adaptive Mesh Refinement/Coarsening)? I would
use such feature for shock-capturing algorithms.

e) Assuming one is able to read a mesh in parallel (Iopx) each proc ends up
with an unordered slice of the mesh. Is there functionallity in STK to
decompose it in parallel and send/receive the mesh data to its appropriate
proc? Would this be related to the rebalance algorithms in STK?

Regards

Carlos Breviglieri
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