feat: opt-in MRT collision for blocked/refined stepping

Additive compile-time COLLISION_MODEL == 2 branches in BlockStep, BlockChannelStep and patch_collide repeat the uniform collide_dispatch MRT sequence (zero forcing, omega clamp, collide_mrt_no_force). SRT statements, including the shifted retained-delta/direct-momentum path, are unchanged under the alternate branch. Guards accept SRT or MRT only; TRT, LES, non-FP32, non-double-buffer and shifted dense/mixed refinement stay rejected. Transfers, subcycling, BFL, raw ledgers, channel closures, shifted-Jet SRT guard and PeriodicBlockStepper are untouched. Existing MRT operator, shifted representation and fixed kinetic rates are reused. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-18 10:26:55 +00:00
parent 9805383f9c
commit 00d7a54829
8 changed files with 168 additions and 10 deletions
@@ -0,0 +1,55 @@
+"""MRT reuse GPU gates. Caller owns GPU admission (CUDA_VISIBLE_DEVICES).
+
+Run: python -m unittest discover -s tests/validation/multigrid -p test_refinement_mrt_gpu.py
+Parity compares the blocked MRT channel root with uniform MRT OneStep: the existing
+pressure-NEQ outlet branch differs by collision model, so SRT is never the reference.
+AMR checks are finite-evolution/split-invariance smoke tests, not benchmark validation.
+"""
+import unittest
+import numpy as np
+
+from CelerisLab.config import LBMConfig
+from CelerisLab.cuda.context import CudaContext
+from CelerisLab.lbm.population_storage import _encode_physical
+from CelerisLab.lbm.refinement_stepper import FixedPatchStepper
+from test_channel_root_gpu import run_root, state
+
+
+class RefinementMRTGPU(unittest.TestCase):
+    def test_uniform_matched_mrt_root(self):
+        with CudaContext(0) as context:
+            for shifted in (False, True):
+                for profile in ("uniform", "parabolic"):
+                    cfg = LBMConfig(nx=24, ny=20, viscosity=.1, velocity=.025, collision="MRT",
+                                    ddf_shifting=shifted, inlet_profile=profile)
+                    initial = _encode_physical(state(cfg.ny, cfg.nx), shifted)
+                    expected = run_root(cfg, context, initial)
+                    self.assertTrue(np.isfinite(expected).all())
+                    for block in ((20, 24), (5, 6), (4, 1)):
+                        np.testing.assert_array_equal(run_root(cfg, context, initial, block), expected)
+
+    def test_amr_mrt_smoke(self):
+        from CelerisLab.body.geometry.circle import CircleGeometry
+        from CelerisLab.body.objects import SimObject
+        center = (24., 16.)
+        body = SimObject(0, geometry=CircleGeometry(*center, 2.15), center=center, radius=2.15)
+        with CudaContext(0) as context:
+            for boundary in ("periodic", "channel"):
+                for shifted in (False, True):
+                    cfg = LBMConfig(nx=48, ny=32, viscosity=.1, velocity=.015 if boundary == "channel" else 0.,
+                                    collision="MRT", ddf_shifting=shifted)
+                    reference = None
+                    for block in ((32, 48), (8, 8), (4, 1)):
+                        with FixedPatchStepper(cfg, (8, 6, 40, 26), context=context, coarse_boundary=boundary,
+                                               base_block=block, fine_block=(8, 8), fine_objects=(body,)) as backend:
+                            backend.initialize(*[state(*level.shape[1:]) for level in backend._levels])
+                            backend.step(8)
+                            raw = backend._download_raw()
+                            for a, mask in zip(raw.values, backend._state):
+                                self.assertTrue(np.isfinite(a[:, mask]).all())
+                            if reference is None: reference = raw.values
+                            else:
+                                for a, b in zip(reference, raw.values): np.testing.assert_array_equal(a, b)
+
+
+if __name__ == "__main__": unittest.main()