Error in residual for cohesive cells when created using transform

[baagaard-usgs]

Describe the bug

The residual is incorrect for one or more cohesive cells when we are using the transform to create the cohesive cells.

To Reproduce

PETSc branch: knepley/pylith
PyLith fork: https://github.com/baagaard-usgs/pylith.git
PyLith branch: feature-create-fault-parallel

make install
cd tests/mmstests/linearelasticity/faults-2d
make export-data -C data
make mmstest_linearelasticity_faults2d
.libs/mmstest_linearelasticity_faults2d OneFaultShearNoSlip::QuadQ1::testResidual --journal.debug=OneFaultShearNoSlip

Expected behavior

Cell 11 Element Hybrid Residual
  | 0. |
  | 1.2 |
  | 0. |
  | 1.2 |
  | 0. |
  | -1.2 |
  | 0. |
  | -1.2 |
  | -1.6 | // Should be 0
  | 0.8 | // Should be 0
  | -0.8 | // Should be 0
  | 1.6 | // Should be 0

[baagaard-usgs]

@knepley I suspect the orientation of one edge is flipped. I will check this and let you know.

[baagaard-usgs]

There is a PETSc branch knepley/fix-hybrid-geometry which has not been merged to main and may have relevant fixes. knepley/fix-hybrid-geometry is old and may be difficult to rebase, so @knepley will create a new branch with the fixes, so we can check if these resolve these errors.

[baagaard-usgs]

@knepley I get similar errors in the Element hybrid residual cell vectors for both TriP1 and QuadQ1 MMS tests. The fault slip constraint equations should be zero, but they are not for 1 cell in the QuadQ1 case and 2 cells in the TriP1 case.

[knepley]

@baagaard-usgs I think I fixed the problem we know about. Pull knepley/feature-plex-transform-cohesive

[baagaard-usgs]

Update

• In the integration of cohesive cells, dim passed to the hybrid Jacobian kernels is spaceDim-1 rather than spaceDim as in the case of the hybrid residual kernels.
• Displacements used in the hybrid residual kernel in TwoFaultsShearNoSlip are incorrect. For some locations, the displacements correspond to vertices that are not adjacent to the fault, similar to the problem we had with one fault.