[petsc-users] Error in DMFieldComputeFaceData_DS with hex elements

[rickcha at googlemail.com]

Dear petsc-team,

I ran into an error when using petscFE in combination with a hex mesh constructed with gmsh. The error message reads:
[0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
[0]PETSC ERROR: Petsc has generated inconsistent data
[0]PETSC ERROR: Not implemented yet

[0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html <http://www.mcs.anl.gov/petsc/documentation/faq.html> for trouble shooting.
[0]PETSC ERROR: Petsc Development GIT revision: v3.10.3-1227-gcd612eedf5  GIT Date: 2019-01-17 05:31:34 +0100
[0]PETSC ERROR: ./standaloneFEM on a arch-linux2-intel-debug named iket127138 by hartig Fri Jan 18 10:49:52 2019
[0]PETSC ERROR: Configure options PETSC_ARCH=arch-linux2-intel-debug --with-debugging=true --with-cc=/home/hartig/intel/bin/icc --with-cxx=/home/hartig/intel/bin/icpc --with-fc=/home/hartig/intel/bin/ifort --download-mpich --download-ml --download-parmetis --download-metis --download-hypre --download-mumps --download-scalapack --download-triangle --download-hdf5 --download-ptscotch --download-chaco
[0]PETSC ERROR: #1 DMFieldComputeFaceData_DS() line 943 in /home/hartig/petsc/src/dm/field/impls/ds/dmfieldds.c
[0]PETSC ERROR: #2 DMFieldCreateFEGeom() line 537 in /home/hartig/petsc/src/dm/field/interface/dmfield.c
[0]PETSC ERROR: #3 DMSNESGetFEGeom() line 2598 in /home/hartig/petsc/src/dm/impls/plex/plexfem.c
[0]PETSC ERROR: #4 DMPlexComputeBdResidual_Single_Internal() line 1520 in /home/hartig/petsc/src/snes/utils/dmplexsnes.c
[0]PETSC ERROR: #5 DMPlexComputeBdResidual_Internal() line 1649 in /home/hartig/petsc/src/snes/utils/dmplexsnes.c
[0]PETSC ERROR: #6 DMPlexComputeResidual_Internal() line 1946 in /home/hartig/petsc/src/snes/utils/dmplexsnes.c
[0]PETSC ERROR: #7 DMPlexTSComputeIFunctionFEM() line 206 in /home/hartig/petsc/src/ts/utils/dmplexts.c
[0]PETSC ERROR: #8 ComputeI2FunctionWithInertia() line 1284 in /home/hartig/cimply/femanalysis.c
[0]PETSC ERROR: #9 TSComputeI2Function() line 1707 in /home/hartig/petsc/src/ts/interface/ts.c
[0]PETSC ERROR: #10 SNESTSFormFunction_Alpha() line 339 in /home/hartig/petsc/src/ts/impls/implicit/alpha/alpha2.c
[0]PETSC ERROR: #11 SNESTSFormFunction() line 4694 in /home/hartig/petsc/src/ts/interface/ts.c
[0]PETSC ERROR: #12 SNESComputeFunction() line 2301 in /home/hartig/petsc/src/snes/interface/snes.c
[0]PETSC ERROR: #13 SNESSolve_NEWTONLS() line 175 in /home/hartig/petsc/src/snes/impls/ls/ls.c
[0]PETSC ERROR: #14 SNESSolve() line 4454 in /home/hartig/petsc/src/snes/interface/snes.c
[0]PETSC ERROR: #15 TSAlpha_SNESSolve() line 101 in /home/hartig/petsc/src/ts/impls/implicit/alpha/alpha2.c
[0]PETSC ERROR: #16 TSAlpha_Restart() line 143 in /home/hartig/petsc/src/ts/impls/implicit/alpha/alpha2.c
[0]PETSC ERROR: #17 TSStep_Alpha() line 217 in /home/hartig/petsc/src/ts/impls/implicit/alpha/alpha2.c
[0]PETSC ERROR: #18 TSStep() line 3664 in /home/hartig/petsc/src/ts/interface/ts.c
[0]PETSC ERROR: #19 TSSolve() line 3847 in /home/hartig/petsc/src/ts/interface/ts.c



Upon investigation, I found that petsc throws the error message because coneSize has a value of six. This is the first thing that puzzles me. I would have expected a cone size of 4 since we are dealing with faces of hex elements. Is it possible that we are on the wrong “level” of the mesh graph somehow? Printing "numFaces“ in the debugger, I get the total number of elements (not 2D faces) I have in my mesh for the hex-case.

I ran the same case with a simplex mesh and found another thing I don’t quite understand: Both times I ran with -petscspace-degree 2. Yet in case of the simplex mesh, I get a polynomial degree of 1 in DMFieldComputeFaceData_DS (“maxDegree”) and in case of the hex-mesh, I get a polynomial degree of 3. In both cases I would have expected the degree to be 2, corresponding to Tet10 and Hex20 elements. I might be confusing two different concepts here. But this was how I understood the documentation until now.

Thanks,
Max
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