Jesus,

The CGNS files we get from Pointwise have only one base, so that should not be 
an issue.  However, sections are needed to contain each cell type, the BCs, and 
zonal boundaries. So, there are always several sections.  The grid that Spencer 
made for you must have multiple sections.  We have to be able to deal with 
grids like Spencer's example or else it's not useful.

B.






________________________________
From: Ferrand, Jesus A. <[email protected]>
Sent: Monday, January 16, 2023 5:41 PM
To: [email protected] <[email protected]>
Subject: DMPlex and CGNS

Dear PETSc team:

I would like to use DMPlex to partition a mesh stored as a CGNS file. I 
configured my installation with --download_cgns = 1, got me a .cgns file and 
called DMPlexCreateCGNSFromFile() on it. Doing so got me this error:

[0]PETSC ERROR: --------------------- Error Message 
--------------------------------------------------------------
[0]PETSC ERROR: Error in external library
[0]PETSC ERROR: CGNS file must have a single section, not 4
[0]PETSC ERROR: See https://petsc.org/release/faq/ for trouble shooting.
[0]PETSC ERROR: Petsc Release Version 3.18.3, unknown
[0]PETSC ERROR: ./program.exe on a arch-linux-c-debug named F86 by jesus Mon 
Jan 16 17:25:11 2023
[0]PETSC ERROR: Configure options --download-mpich=yes --download-hdf5=yes 
--download-cgns=yes --download-metis=yes --download-parmetis=yes 
--download-ptscotch=yes --download-chaco=yes --with-32bits-pci-domain=1
[0]PETSC ERROR: #1 DMPlexCreateCGNS_Internal() at 
/home/jesus/Desktop/JAF_NML/3rd_Party/PETSc/petsc/src/dm/impls/plex/cgns/plexcgns2.c:104
[0]PETSC ERROR: #2 DMPlexCreateCGNS() at 
/home/jesus/Desktop/JAF_NML/3rd_Party/PETSc/petsc/src/dm/impls/plex/plexcgns.c:60
[0]PETSC ERROR: #3 DMPlexCreateCGNSFromFile_Internal() at 
/home/jesus/Desktop/JAF_NML/3rd_Party/PETSc/petsc/src/dm/impls/plex/cgns/plexcgns2.c:27
[0]PETSC ERROR: #4 DMPlexCreateCGNSFromFile() at 
/home/jesus/Desktop/JAF_NML/3rd_Party/PETSc/petsc/src/dm/impls/plex/plexcgns.c:29

I looked around mail archives for clused and found this one 
(https://lists.mcs.anl.gov/pipermail/petsc-users/2018-June/035544.html). There, 
Matt provides a link to the source code for DMPlexCreateCGNSFromFile() and 
another (seemingly broken) link to CGNS files that can be opened with the 
former.  After reading the source code I now understand that it is hardcoded 
for CGNS files that feature a single "base" and a single "section", whatever 
those are.

After navigating the CGNS documentation, I can sympathize with the comments in 
the source code.

Anyhow, I wanted to ask if I could be furnished with one such CGNS file that is 
compatible with DMPlexCreateCGNSFromFile() to see if I can modify my CGNS files 
to conform to it. If not, I will look into building the DAG myself using DMPlex 
APIs.


Sincerely:

J.A. Ferrand

Embry-Riddle Aeronautical University - Daytona Beach FL

M.Sc. Aerospace Engineering

B.Sc. Aerospace Engineering

B.Sc. Computational Mathematics


Phone: (386)-843-1829

Email(s): [email protected]

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