138 lines
8.7 KiB
Plaintext
138 lines
8.7 KiB
Plaintext
Fixed 2:1 patch preparation — implementation handoff, 2026-10-13
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Delivered: one production module, src/CelerisLab/lbm/refinement.py (138 lines),
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and tests/unit/test_refinement.py (167 lines). No existing code was modified.
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The API produces real layer geometry and compact exchange tables. It does not
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advance a coupled simulation; numerical coupling remains a joint review item.
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Usage (existing config, no CUDA required):
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from CelerisLab.config import load_lbm_config
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from CelerisLab.lbm.refinement import FixedPatch2D
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cfg = load_lbm_config()
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patch = FixedPatch2D.from_config(cfg, (4, 4, 12, 12))
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patch.check_synchronization(0, 0, phase="postcollision_g")
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The supplied configuration must satisfy the documented initial backend subset.
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Bounds are (x0,y0,x1,y1), half-open, in coarse cells. Shapes are (ny,nx).
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Current architecture and data path
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Simulation
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-> LBMConfig -> compiler_v2 -> generated per-domain module
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-> LBMField: Q-major GPU DDF buffers, flags, host mirror, macro buffers
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-> LBMStepper: OneStep + buffer swap, completed coarse-step count
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-> pull -> physical BC -> collision -> stored postcollision_g
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New opt-in preparation path (no change to the above path):
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LBMConfig -> FixedPatch2D.from_config
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-> copied/validated config; coarse/fine tau and layer dimensions
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-> fine_kind: active / inner halo / outer halo (uint8)
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-> paired ghost_fine/ghost_coarse cell indices (uint32)
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-> coalesce_coarse + four coalesce_fine population slots (uint64)
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-> future transfer/step kernels (not implemented in this increment)
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Choices and actual implementation
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The initial contract is D2Q9/SRT/FP32/unshifted/double_buffer, without LES.
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Existing Python lattice descriptors and CUDA Q-major index conventions are
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reused. Existing configuration is copied before validation; both layers must
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respect its omega guards. Fixed 2:1 acoustic scaling gives tau_f=.5+2*(tau_c-.5).
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Fine coordinates use the patch's physical offset, dx=dt=.5 and a four-cell halo.
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Only the outer coarse ring is searched for closed-midpoint coalescence targets;
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all eight corner-pass links are included. No coarse-domain-sized masks or DDF
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arrays are allocated. Standard [4,12)^2 patch tables total 7136 bytes; enlarging
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only the coarse grid leaves table size unchanged. Arrays are contiguous/read-only.
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An explicit import enables the API; no eager package imports or default-path
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branches were added. No tree, dynamic AMR framework, new solver, field hierarchy,
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fake stepper, fine LBMField allocation or premature config/runtime switches.
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The synchronization method checks count/phase metadata only. It does not inspect
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populations or prove that a caller's buffer really holds g. Two coarse cells of
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geometric margin certify donor indices, not fluid ownership or physical BC safety.
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Runtime forcing, objects and domain BCs still need explicit coupling validation.
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Numerical coupling proposal for Claude/Grok joint review — NOT implemented
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Let F_n be the reference arrival state and G_n=C(F_n) the production state.
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Start from stored G_n, without re-colliding it:
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1. Explode coarse G_n into fine halo once (unscaled, as in pinned CPUREF).
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2. Fine hop 1 -> arrival F_(n+1/2); collide fine active cells once.
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3. Fine hop 2 -> arrival F_(n+1); fine halo ghosts never collide.
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4. Coarse pull -> provisional arrival; replace incoming interface populations
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with the four-child fine-halo average, including corner-pass links.
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5. Collide coarse active cells once and fine active cells a second time,
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publishing synchronized G_(n+1). Equivalent fusion may preserve this order.
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Thus each coarse interval has one coarse collision and two fine collisions.
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Initialization must establish G_0 consistently; no extra per-step collision may
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be added to match a reference plot. Comparing C(F_ref) to production G is a test
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observation conversion, not a production step. Do not overwrite postcollision
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coarse slots with uncollided coalescence after ordinary OneStep has finished.
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The current fused kernel therefore needs a reviewed insertion point before its
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collision, with masks preserving covered/halo semantics. Its normal inlet ghost
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collision behavior is separate from the fine-halo rule above.
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First numerical scope proposed: fixed, unforced, object-free doubly periodic
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patch, same baseline tau pair; <=8-step same-phase CPU/GPU comparison after
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the coupling design is jointly reviewed. Reuse existing collision/layout
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helpers rather than reproduce a solver. Simulation currently constructs channel
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flags/wall corrections, so reusing its default initializer does NOT create this
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periodic fixture. Boundary selection and level-module ownership must be agreed
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before attaching a coupled backend to Simulation. No GPU budget was requested
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or consumed in this architecture-only increment; any later GPU run needs an
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occupancy check and a specific allocation budget before execution.
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The observed ~2.9% excess shear decay does not block topology preparation or a
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bounded equivalence implementation, but remains an interface-accuracy concern.
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Neither a future <=8-step comparison nor this geometry test establishes 32-step
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accuracy, convergence or a stress-transfer mechanism. No nonequilibrium scaling
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or time-interpolated ghosts were mixed into the pinned route. Claude's previous
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local_stress implementation-code review remains incomplete.
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Reference/architecture guard traceability
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Read .github/skills/lbm-ref-architecture-guard/SKILL.md; no applicable AGENTS.md
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was found in the project/source/test ancestor paths. Concrete source findings:
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- src/CelerisLab/lbm/descriptors.py and kernels/core/layout.cuh define paired
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D2Q9 and q*N+y*nx+x; maps use them rather than a second direction convention.
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- src/CelerisLab/lbm/kernels/step/one_step_double.cu fuses pull/BC/collision;
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src/CelerisLab/lbm/stepper.py swaps the stored g buffers afterward.
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- src/CelerisLab/lbm/field.py builds channel topology and allocates full field
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resources: unsuitable as an implicit fine-patch initializer.
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- ref/lbmpy/src/lbmpy/relaxationrates.py: relaxation_rate_scaling agrees with
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tau_f=.5+2*(tau_c-.5); no population rescaling is inferred from this formula.
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- ref/palabos/src/multiGrid/multiGridGenerator2D.hh: two fine substeps and
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separate interface processors support keeping topology separate from steps.
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Its interpolation/rescaling is a different scheme and was NOT adopted.
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- Pinned CPUREF-0.3 supplies the reviewed closed-corner volumetric geometry.
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Its SHA remains bba2a06a9f6517b32079ffff15e4060d8c3b7ed35f16ca134e1877226c9e4e1e.
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Review and validation
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Independent local subagent /root/refinement_review read the production module
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and related sources and found no blocking issue. Its two suggestions were
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adopted: explicitly distinguish fine halo ghosts from inlet ghosts, and cover
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the smallest 1x1 patch at the two-coarse-cell margin. This is not a completed
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Claude/Grok review of the new coupling proposal.
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Ran only tests/unit/test_refinement.py: 9/9 passed, no numerical advance.
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Coverage: all exchange maps against pinned reference, eight corner passes,
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400 unique fine-slot reads, translated rectangle geometry/child centers,
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minimal halo edges, tau/config isolation, compact read-only arrays, index
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overflow rejection before allocation, unsupported backend/omega guards,
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phase/count rejection, exact source provenance and no CUDA/Simulation imports.
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No old diagnostics, physical matrix, Jet replay or GPU tests were rerun.
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Python 3.10.13 / NumPy 1.26.4 from existing pycuda_3_10 environment.
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PYTHONPATH=/home/frank14f/CelerisLab/src; process-only BLAS thread=1, bytecode
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disabled, user site disabled, assertions enabled. Parent and child limited by
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prlimit to 256 MiB address space, 2 MiB output file and core=0.
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Peak child RSS 36.00390625 MiB, parent 18.5 MiB; child elapsed .274485 s;
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combined test stdout/stderr 873 bytes. Full commands, times and source hash
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are in validation.json; actual unittest output is validation.txt.
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Audit artifacts
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baseline.json freezes HEAD, full dirty status and 303 old-file hashes, including
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all preceding validation materials. Scope excludes read-only ref, symlinks and
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bytecode, as stated in the baseline. incremental.patch is only the two new code
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files, relative to the preserved starting tree. manifest.json records final old
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file checks and new paths/sizes/SHA. No staging, commit, push or DynamisLab work.
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Stopped at the numerical coupling joint-review point.
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Authorization, verbatim as relayed by the coordinating thread
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<transcript_evidence>
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user（Sentinel_ed1ee5edd5e88191a1aaa4d710ce523f）: 推进吧，～/CelerisLab就是开发环境，可以改动，只要符合架构风格。遇到问题可以用undermind看文献，也可以让grok搜索互联网信息，还可以参考开源项目。
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user（Sentinel_d0d3a42b2c088191aa8aebc105fb1b27）: 允许，你用GPU验证都行
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</transcript_evidence>
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