CelerisLab/docs/supported_settings.md

Supported settings: 2D Jet + fixed multilevel refinement (candidate c95a7ba)

Every entry names the guard that enforces it (file:line at c95a7ba) and, where one exists, an existing test that exercises it. A setting not listed here is not claimed. Observations at the end are tied to the exact case in which they were measured; they are not general bounds.

Lattice, storage, collision

Setting	Supported	Guard
Dimension / lattice	2D D2Q9 only (3D refinement is future work)	lbm/refinement.py:65, lbm/kernels/blocks.cu:25, lbm/kernels/refinement.cu:26
Precision / streaming	FP32 storage, double buffer	same guards
Collision on refinement levels	SRT or MRT; TRT and LES rejected	lbm/refinement.py:65 (re-checked for fine boundaries at lbm/refinement.py:457)
Shifted (ddf_shifting) storage	only when every level is blocked; dense or mixed rejected	lbm/refinement_stepper.py:198, :469; lbm/kernels/refinement.cu:26 (dense patch kernel unshifted only)
Fine relaxation	1/tau_fine must lie inside the configured omega guards	lbm/refinement.py:80
Uniform blocked backend PeriodicBlockStepper	doubly periodic, SRT only, stationary passive circles	lbm/block_stepper.py:84, :91, :45-:67

Tests: tests/unit/test_refinement_mrt.py, tests/validation/multigrid/test_refinement_mrt_gpu.py, tests/unit/test_shifted_storage.py, tests/unit/test_shifted_block_operators.py.

Refinement hierarchy (FixedPatchStepper(cfg, *, context, refinements, ...))

Setting	Supported	Guard
Depth	at least one refinement level; one entry per level in level_blocks/level_objects/level_jets	lbm/refinement_stepper.py:72, :75
Single L1 rectangle	two-coarse-cell margin to the domain edge	lbm/refinement.py:73
Several L1 rectangles (union)	require level_blocks[0] and level_blocks[1]; transfers must close (dependency checks, no fixed gap rule)	lbm/refinement_stepper.py:84; lbm/refinement.py:283-:295
Nested levels	depth >= 3 must be all blocked; a blocked level requires blocked levels below; a scalar child needs a scalar parent	lbm/refinement_stepper.py:82, :87; lbm/hierarchy.py:54
Nested transfer support	child only over inherited ACTIVE cells, donors/receivers uncovered ACTIVE, no child over the parent restriction footprint	lbm/refinement.py:391-:407
Tile shape	positive (by, bx); the level allocation must be divisible by the tile (no partial tiles yet)	lbm/refinement_stepper.py:78, lbm/refinement.py:246 (shape); lbm/blocks.py:134 (divisibility)
Coarse boundary	periodic, slot_reservoir or channel	lbm/refinement_stepper.py:177
slot_reservoir	on-site velocity bottom slot, reservoir top, velocity 0, 2 <= slot width < nx, patch rows 4..ny-4	lbm/refinement_stepper.py:205, :212; lbm/refinement.py:546
channel	all levels blocked; Zou-He inlet, pressure-NEQ outlet, stationary bounce-back walls; transfers away from the closure	lbm/channel.py:22, :26, :43, :54
Explosion	constant (default); projected_linear only periodic, all-blocked SRT, no bodies/Jets, no LES (experimental)	lbm/refinement_stepper.py:188, :193
L2 runtime remap (remap_child)	periodic three-level L2 sets only, no L0/L1 bodies, identical pinned boundary	lbm/refinement_stepper.py:557, :567-:581

Tests: tests/unit/test_refinement_three_level_multipatch.py, tests/validation/multigrid/test_refinement_multipatch.py, test_refinement_three_level.py, test_refinement_three_level_multipatch_gpu.py, test_refinement_blocked_base.py, test_refinement_blocked_fine.py, test_channel_root_gpu.py, tests/unit/test_channel_root.py, tests/unit/test_projected_pair_stepper.py, test_runtime_child_remap_gpu.py, test_pinned_body_remap_gpu.py.

Bodies and Jets on refined levels

Setting	Supported	Guard
Bodies	stationary circles without sensor/force-region roles, entirely inside the patch union, fully resolved, disjoint, stencil away from the two-hop transfer footprint	lbm/refinement.py:474-:542
Level	not on L0; only on the finest level of a nested hierarchy	lbm/refinement_stepper.py:80, :89
Jet condition	velocity only; pressure is reserved and raises NotImplementedError	body/jets.py:148, :150
Jet geometry	each Jet selects resolved links of exactly one stationary body; no Jet/Jet or Jet/SurfaceActuation overlap; abs(amplitude) < 1 lattice	body/jets.py:155, :175, :177, :255, :261, :263
Jets with shifted storage	only in the all-blocked stepper with SRT and no LES	body/jets.py:249
SurfaceActuation	unshifted storage only	body/objects.py:155
Raw boundary exchange (force)	blocked body levels only; the window ledger requires observe_raw_exchange	lbm/refinement_stepper.py:264, :269
Checkpoint with Jets	refused	simulation.py:687

Raw exchange is the cut-link momentum reaction (wall + aperture), not a validated nozzle thrust or stress load. Jet amplitude is a lattice velocity, not a flow rate.

Tests: tests/unit/test_jets.py, test_jets_review.py, test_shifted_jets.py, test_raw_exchange.py, tests/validation/multigrid/test_refinement_jets.py, test_shifted_jets_gpu.py, test_raw_exchange_gpu.py, test_exchange_window.py, test_fine_surface_gpu.py.

Observations from specific tested cases (not general bounds)

• SRT channel root vs uniform OneStep, strict-parity test tests/validation/multigrid/test_channel_root_gpu.py::ChannelRootGPU::test_uniform_matched_root: in one of its 18 sub-cases (2 storage modes x 3 profile/clamp/damp settings x 3 blocks; which one is not recorded), 1 of the 4320 compared values differs, max abs 2.33e-10, max rel 1.77e-7 (about 2 ULP). The test remains failed; its cause and any general bound are unresolved.
• MRT root parity test tests/validation/multigrid/test_refinement_mrt_gpu.py::RefinementMRTGPU::test_uniform_matched_mrt_root (12 sub-cases: 2 storage modes x 2 profiles x 3 blocks, default outlet settings) passed bitwise in the Horsea GPU runs at K1 7813334 and on the combined tree f4372a8 (2026-10-21).
• Periodic Taylor-Green Re 100, measured at 36ffc8b1 (V3 matched pair, N128 depth 2): every per-sample screen passed; the constant explosion's aggregate worst velocity L2, 0.004418, exceeds its preregistered 0.002 budget, while projected_linear passed that budget.
• Curved-wall pressure (pilot harness, exact-q analytic annulus, tau 0.8): the coarse swirl r1 case exceeded its terminal density-gain cap (1.105e-4 vs 1e-4), so the frozen 9-case matrix is NOT_ESTABLISHED. No validated fix exists. This is a pilot harness, not production code.
• DFG 2D-1 Re 20 (V4, SRT, t* 60, pressure-NEQ outlet and local Zou-He inlet): refined and uniform runs were NOT_STEADY under the frozen steady rule, so no interval verdict was given.

Not supported in this release

3D, dynamic/automatic AMR (tagging, time-varying hierarchies beyond remap_child), moving bodies on refined levels, pressure Jets, Jet checkpoints, LES or TRT on refined levels, partial (non-dividing) tiles.