7.1 KiB
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 focused GPU run at K17813334(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.