Boussinesq PETSc Validation Results

This page records the current analytical-validation status after routing the solver = "boussinesq" analytical cases through the PETSc Boussinesq runtime.

The public validation label remains boussinesq. Internally, steady analytical Boussinesq cases now use a pure steady PETSc SNESVI solve with flow.runtime_backend = "petsc" and flow.surface_interaction_model = "vi_obstacle". Transient analytical Boussinesq cases now use PETSc TS with SNESVI through flow.surface_interaction_model = "ts_vi_obstacle".

Latest Automated Results

The following commands were run on 2026-05-06 in the WSL PETSc environment through install/enter_wsl_dev.sh --headless.

Check	Command	Result	Duration
Pytest PETSc analytical validation suite	python -m pytest tests/validation/analytical -m petsc -q --tb=short	26 passed, 66 deselected	158.92 s
Documentation validation batch for solver=boussinesq	python -m validation_cases.run_cases --solver boussinesq --regime both --no-show --stop-on-error --report-json validation_cases/reports/latest/boussinesq_both.json --timeout 1800	21/21 cases passed	659.8 s

The committed report consumed by the validation gallery is: validation_cases/reports/latest/boussinesq_both.json. It was generated at 2026-05-06T07:41:24.118686+00:00 and records failed_case_count = 0.

Validation Gallery Pages

Open these pages first in the generated HTML build:

• Validation Benchmarks shows the refreshed Boussinesq batch line: 21/21 cases passed.

• Boussinesq Hillslope Interception 1D is the main PETSc VI obstacle diagnostic page.

• Capability Gallery is the gallery entry point.

The hillslope interception figure was regenerated with the PETSc method line in the plot footer.

Fig. 80 Boussinesq hillslope interception validation, rendered for the documentation gallery with the PETSc VI obstacle method annotation.

Case Coverage

These 21 analytical validation cases use the PETSc-backed Boussinesq route in the latest batch report.

Regime	Documentation page	Method
Steady	Boussinesq Circular-Island Piecewise-K 2D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Boussinesq Divide-Fixed-Head Piecewise-K 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Boussinesq Fixed-Head Piecewise-K 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Boussinesq Hillslope Interception 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Boussinesq Sloping-Substratum Constant-Thickness 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Boussinesq Sloping-Substratum Fixed-Head 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Boussinesq Sloping-Substratum Uniform-Recharge 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Boussinesq Uniform-Recharge Piecewise-K 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Dupuit Circular-Island Ocean 2D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Dupuit Divide-River 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Dupuit Fixed-Head 1D	PETSc SNESVI, pure steady, vi_obstacle
Steady	Dupuit Uniform-Recharge 1D	PETSc SNESVI, pure steady, vi_obstacle
Transient	Boussinesq Hillslope Recharge-Step Interception 1D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Brutsaert Recession Boussinesq Thin 1D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Brutsaert Recession Linearized Deep 1D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Late-Time Unconfined Pumping 2D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Linearized Unconfined Boundary Piecewise 1D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Linearized Unconfined Boundary Step 1D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Linearized Unconfined Recharge Periodic 1D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Linearized Unconfined Recharge Step 1D	PETSc TS + SNESVI, ts_vi_obstacle
Transient	Linearized Unconfined Recharge Step Deep 1D	PETSc TS + SNESVI, ts_vi_obstacle

Hillslope Interception Diagnostic

The migration is mostly a runtime substitution. The main exception remains the steady hillslope interception case. The PETSc VI solve is numerically clean, but the interception position differs from the historical no-drain analytical intersection.

Quantity	Current value	Interpretation
Analytical interception x	244.776 m	Historical no-drain Boussinesq profile intersected with topography.
PETSc VI numerical interception x	285.000 m	Contact front from the hard obstacle solve.
Interception x error	40.224 m	Below the current 45 m acceptance threshold.
Cross-row head spread	8.88e-16 m	Quasi-1D uniformity is preserved.
Topography overshoot	0.0 m in the PETSc diagnostic run	The obstacle constraint is respected.

This offset is not interpreted as a nonlinear convergence failure. The analytical reference solves a no-drain profile and then intersects it with the topography, while the PETSc VI method solves a constrained obstacle problem with an active surface-contact zone and surface reaction.

Related Developer Notes

• docs/developers/boussinesq_petsc_vi_hillslope_interception_analysis.md documents the detailed hillslope interpretation.

• docs/developers/boussinesq_petsc_complementarity_nancon_diagnostic.md documents earlier PETSc complementarity diagnostics on a larger numerical scenario.