57 Commits

Include renames

Author	SHA1	Message	Date
Omar SobhandClaude Fable 5.1	415c32ab04	overset mesh: the flat-tip outline (P5-3 option B) — cylinder_flag_outline_deformed_tip / cylinder_flag_patch_deformed{,_from}_tip take the tip's corner radius (t = the recorded semicircle, bit for bit; smaller = the benchmark's flat face between corner arcs sampled at the wall spacing, point count fixed across the deformation, the tip's corners kept off the hull source); pins: corner t reproduces the recorded outline, the 2.5 mm outline has the exact area excess with no collapsed spacing, the O-grid builds straight and at ± 80 mm cold and warm at ny 41/62; harness knob RTX_FSI2O_TIP_CORNER (default 0.01) on the cold and warm builds, printed in both headers; pinned-toolchain fmt on touched crates ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01LzcjQX7tvgn87CQCyg9Cfr	2026-09-13 22:22:08 -05:00
Omar SobhandClaude Fable 5.1	754dcd3679	overset: the energy pin (P5-3) — the rigid cylinder + flag outline pitching about the cylinder's centre in still fluid on the moving patch at the FSI2 fluid and grid; per-cycle net fluid work on the body (must be ≤ 0 at every h), gross +/− split, and the last-two-period moment fit → added inertia + rotational damping; knobs RTX_OVERSET_NY / _EP_PERIODS / _EP_TIP / _EP_F; ny 41 one-period smoke: net −5.62 J/m, damping 56.9 N·m·s/m (π c θ0² ω = 5.6 J, self-consistent), 21 s ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01LzcjQX7tvgn87CQCyg9Cfr	2026-09-12 20:57:58 -05:00
Omar SobhandClaude Fable 5.1	33534ee688	overset added-mass pin (P5-3): a no-slip cylinder on the moving patch oscillating in a closed box of still fluid, the force fitted over the last two periods — C_m = 1.069 (n = 32) / 1.097 (n = 64) against Stokes's 1.064 plus box blockage: the composite's unsteady pressure response is right, the FSI2 lift excess is not the unsteady term's scale ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-09 18:01:53 -07:00
Omar SobhandClaude Fable 5.1	3e019d1491	P5-3 instruments: per-region wall loads on saved instants (top / bottom / tip arc / fillets+cylinder — drag, lift, normal-traction mean/min/max; RTX_FSI2O_AUDIT_FACES, RTX_FSI2O_AUDIT_ONLY) and the patch-thickness knobs (RTX_FSI2O_PATCH_OFFSET / _PATCH_ROWS, RTX_OVERSET_PATCH_OFFSET / _PATCH_ROWS; save tags carry the offset) — the overlap band sat at a fixed number of cells (6 h) and moved inward in metres with refinement ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-08 05:35:14 -07:00
Omar SobhandClaude Fable 5.1	06229dd9a2	rtx-cfd: the deformed cylinder–flag build's hull source carries the deformed outline — the cylinder + tip disc alone give the chord under a bent flag's convex side (P5-2 died at tip −35 mm with the patch 4.4 h thick where 6 h was asked, an acceptor's donor on a prescribed face); the death reproduced from the last saved instant by extrapolating the interface (fsi2_overset_probe_death_from_instant, with the failing acceptor's ray geometry and the overlap depths that build) and gone with the fix at every τ; RTX_FSI2O_ROWS; the zero-displacement mesh gate at 1e-5 (the pipeline's), the outline gate 1e-12 unchanged ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 10:25:46 -07:00
Omar SobhandClaude Fable 5.1	3a68048934	rtx-cfd: cylinder_flag_patch_deformed_from — the warm-started regeneration (P5's cost lever): the previous patch's interior and its outer ring projected onto the new offset polygon as the start, and an IDEMPOTENT build (one Winslow sweep alternating with the ray re-spacing; the P4-0 one-shot is not a fixed point — measured as the interior moving 0.05 h per build at rest), so a base converged as that map's fixed point stays put (9e-11 h at rest) and each build tracks the outline (interior/wall motion 0.99–1.14, worst angle 74.7°, wall row 0.37 h) 4.5× faster than the cold build; the rigid generator untouched (pins pass); fsi2 overset harness: RTX_FSI2O_WARM_SWEEPS with the converged base as the initial patch and the committed step's mesh as each step's warm start ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 09:10:05 -07:00
Omar SobhandClaude Fable 5.1	2ed36c3a8c	P5-1 instruments: the overset fluid saves/loads its rigid-phase state (RTX_FSI2O_SAVE / _LOAD — a coupling experiment then costs seconds, not the 12-minute rigid march), dumps the interface edges when the composite refuses a patch (RTX_FSI2O_DUMP_DIR, at the advance where the overlap is rebuilt), the release time is the fluid's clock; patch_cylinder_flag_deformed: cells inside the flag are holes at small bends and both sweep counts (the cantilever shape does not reproduce the P5-1 death — the CSVs show a coupling runaway), and a dumped-edges reproduction test ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 08:09:56 -07:00
Omar SobhandClaude Fable 5.1	d74571e21a	rtx-cfd: the deformed cylinder–flag outline's edge fractions come from the UNDEFORMED straight edge (x_tip_ref), so the patch topology is the mesh family's and not the deformation's — the P5-1 gate run died at the first bend with set_mesh refusing 143 → 144 wall cells; the P5-0 test now gates ns across amplitudes (143 at −80 / +40 / +80 mm) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 07:34:26 -07:00
Omar SobhandClaude Fable 5.1	f0b2563bf8	P5-1: FSI2 with the fluid on the overset — fsi2_harness/overset.rs (the background without a body, the cylinder–flag patch regenerated around the deformed flag every pass via set_patch_mesh, the wall velocity from the interface velocities along the wetted polygon, the load from the patch's wall faces into WettedSurface::transfer_load — no probes, no clamp, no smoothing), fsi2_harness/overset_march.rs (the harness's rigid phase / release / subiterated coupling with its acceptance rule, no rescue machinery, death returned not panicked), tests/turek_hron_fsi2_overset.rs (RTX_FSI2O_* knobs); rtx-cfd: CurvilinearPisoSolver::wall_tractions (per-face pressure + full-stress traction, surface_force sums the same terms bit-identically); Interface::edges (bottom/tip/top for the generator); cylinder_flag_mms RTX_CF_BEND (P5-0 gate iv: Stokes orders 2.14 / 2.09 on the flag bent to 80 mm) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 07:16:53 -07:00
Omar SobhandClaude Fable 5.1	c2451fbacf	rtx-cfd: P5-0 — cylinder_flag_patch_deformed / cylinder_flag_outline_deformed: the O-grid around the cylinder and the FEA's deformed flag edges (FlagEdges bottom / tip / top), edges resampled at the rigid outline's graded arclength spacing, root fillets from the rigid construction, the tip semicircle from the deformed tip's centre and axis; the O-grid body factored out (o_grid_from_outline, hull_source) and the rigid generator kept bit-identical (its pins pass); gates: zero displacement reproduces the rigid outline to 6e-17 (mesh 2.5e-8 through the hull/Winslow pipeline, recorded), ±80 mm cantilever shapes valid at 80° with wall row 0.43 h, along-body 0.196 h, wall nodes on the edges to 6e-17, ny = 41 overlap builds ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 07:10:01 -07:00
Omar SobhandClaude Fable 5.1	cee9adef26	rtx-cfd: overset_cfd23 RTX_OVERSET_CFD23_PHASE=N — the momentum chain's stages sampled every N steps and averaged over the window; over whole shedding periods the unsteady terms vanish and the averaged chain is exact (the patch balance's unstored unsteady term included) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 04:14:55 -07:00
Omar SobhandClaude Fable 5.1	1a8f4aaebe	rtx-cfd: OversetPisoSolver::set_time; overset_cfd23 resumes a march from a saved field (RTX_OVERSET_CFD23_RESUME_T, _T_START) — CFD3 ny = 82's wake is still growing at t = 6–9 s (half-window amplitudes 187 / 339), the settled amplitude needs t = 15 ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-07 00:08:27 -07:00
Omar SobhandClaude Fable 5.1	ec17217e9e	rtx-cfd: overset_cfd23 RTX_OVERSET_CFD23_ND=explicit — the patch's across-diffusion explicit (dt limit then includes the n-spacing) for the 10 mm damping-floor probe; field tags carry it ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-06 20:44:07 -07:00
Omar SobhandClaude Fable 5.1	ce3cbcce57	rtx-cfd: overset_cfd23 — Turek–Hron CFD2/CFD3 on the overset (the harness's ramped inflow from rest, TVD background and patch, 3-round cap), loads by the patch wall stress with the solver-flux-form box and the CV formula beside it as window statistics, CFD3 frequency from lift crossings, the solver-metric momentum chain at the final state (solved-face residual is the pin), save/load of the fields by case; momentum_residual checks the far-upwind neighbours explicitly under a limited background (the van Albada limiter swallows a NaN silently) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-06 17:10:18 -07:00
Omar SobhandClaude Fable 5.1	36af178980	rtx-cfd: overset_cfd1 RTX_OVERSET_ROWS — the overlap depth (patch rows kept non-hole below the acceptor row, default 4) as a knob for the §5.11 band probe; saved-field tags carry it; rows ≤ 3 are refused by the map at ny = 41 (acceptor donors reach the hole at the flag tip) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_0116sg1Qz1gMv9hdcKP1XUam	2026-09-06 15:30:31 -07:00
Omar SobhandClaude Fable 5.1	4c000266d9	rtx-cfd: overset momentum residual carries its pieces per ring face (time, convective, diffusive, pressure); overset_cfd1 offline probes on the saved fields — RTX_OVERSET_CFD1_FRONT dumps the cylinder-front faces by piece, RTX_OVERSET_CFD1_RAW re-evaluates the ring on the raw interpolated stamping without balance_fringe_fluxes (the balance is not the ring's source: +0.241 raw vs +0.247 balanced at ny = 41 upwind) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-06 14:37:08 -07:00
Omar SobhandClaude Fable 5.1	0215c7d6a5	rtx-cfd: CurvilinearPisoSolver::momentum_balance — the patch's own momentum balance on its solved cells in the scheme's fluxes (outward ρFu_f with the predictor's face value, Laplacian-form μ∇u·S on the solved/acceptor interface and the wall, the least-squares pressure volume sum vs the face-pressure integrals); flux_force, wall_force, pressure_defect δP; overset_cfd1 prints it and the acceptor band's mismatch, saves the patch flux, and RTX_OVERSET_CFD1_LOAD=dir runs the diagnostics offline on saved fields ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-06 14:13:04 -07:00
Omar SobhandClaude Fable 5.1	e31576d543	rtx-cfd: OversetPisoSolver::solver_metric_force — the box force in the predictor's own flux form (upwind convective, diffusive, cell pressure on the momentum control volumes' faces, minus the unsteady term); box-independent to rounding in the active region (five boxes spread 2e-12 at step 5 vs the CV formula's ±0.5 %); overset_cfd1 prints wall − box = ring Σr + rest and saves the settled fields under RTX_OVERSET_CFD1_SAVE ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-06 13:47:43 -07:00
Omar SobhandClaude Fable 5.1	6f9b0d43b2	rtx-cfd: OversetPisoSolver::momentum_residual — the background predictor's own staggered stencil (u_rhs/v_rhs, factored out of the predictor bit-identically) evaluated on every face of a NaN-masked field; solved faces read rounding, the active–fringe interface reads the composite's pressure level offset δ·h (cancels in the sum), prescribed fringe–fringe / fringe–hole faces read the stamping's momentum injection; hole ghosts (p, u, v) from a band widened three rows into the hole make every ring face evaluable; overset_cfd1 prints the buckets, the ring x-bands and δ at the settled state; pin: residual vanishes on the solved faces ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-06 13:25:14 -07:00
Omar SobhandClaude Fable 5.1	cbec40b999	rtx-cfd: overset_cfd1 prints five CV boxes (all outside the fringe ring), the wall pressure/viscous split and the fringe extents at the settled state ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-06 10:14:43 -07:00
Omar SobhandClaude Fable 5.1	134ac03870	rtx-cfd: OverlapMap::region_force — momentum flux into a background region (control-volume face formula, one-sided next to holes); overset_cfd1 prints the four momentum routes (CV box, ring outer, hole boundary, wall) and their defects at the settled state ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-06 09:08:01 -07:00
Omar SobhandClaude Fable 5.1	5f780447de	rtx-cfd: PatchConvection::TvdVanAlbada — van Albada deferred correction on the curvilinear predictor (downwind-side linear weight, gradient-ratio r over the face d lengths, far-upwind across the opposite face, boundary faces upwind); annulus MMS orders 2.10/1.69 at 0.24× upwind; cylinder-flag MMS orders 1.98/1.97 (1.06× upwind — diffusion-dominated, recorded); knobs RTX_OVERSET_CFD1_TVD, RTX_OVERSET_MAX_ROUNDS, RTX_CF_SCHEME ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-06 00:21:48 -07:00
Omar SobhandClaude Fable 5.1	02c855b9c4	rtx-cfd: overset Schwarz stall rule guarded (fires only within 10× the tolerance) — unguarded it cut CFD1's transient at round 3 every step and the coupled march diverged at ny=62 (pressure 4e4 → 1e140 by step 450); CFD1 harness knobs (stall, step cap, trace) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-05 21:01:57 -07:00
Omar SobhandClaude Fable 5.1	00f73eb70a	rtx-cfd: overset CFD1 harness — the steady-march stall rule (stall_rounds 2) actually enabled (the previous commit's edit had missed its anchor) ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-05 20:28:25 -07:00
Omar SobhandClaude Fable 5.1	9761cf2319	rtx-cfd: overset P4 — CFD1 on the composite (tests/overset_cfd1.rs): ny=41 wall drag 15.2156 (+6.46%), lift 1.0879 (−2.78%), CV drag 15.528 (+8.64%), routes 2.0% apart (staircase +10%); 28550 steps, 2099 s at dt 4.57e-4 with 5.0 Schwarz rounds mean (stall rule off) — steady-march stall rule on for the next rungs ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-05 20:27:52 -07:00
Omar SobhandClaude Fable 5.1	45ff34da8f	rtx-cfd: overset P4-0 — the O-grid around the Turek–Hron rigid body (cylinder + flag), gated ... patch_gen::{cylinder_flag_outline, cylinder_flag_patch, winslow_smooth, respace_rays} (+ convex_hull, offset_convex_polygon, nearest_on_polyline): the outline CCW then reversed to clockwise (tip semicircle 16 cells, junction fillets of a FIXED radius with 3 cells, straights graded 0.3 h → h, cylinder arc at h); the outer ring the 6 h normal offset of the body's convex hull; initial pairing by the inner point's normal offset projected onto the hull offset (an arclength-proportional pairing folded the transfinite grid at the tip: rays crossed where the curvatures differ); Winslow (TTM) smoothing of the interior with the outer nodes SLIDING along the hull offset (each re-placed at the nearest point to the extrapolated ray), then re-spacing along the smoothed rays to the across stretch. Gates (tests/patch_cylinder_flag.rs): ny = 41/62/82 → 143×12 / 183×12 / 225×12 cells, positive, wall row 0.23 h (fillet max 0.37 / 0.43 / 0.50 h), worst non-orthogonality 76.6 / 69.1 / 63.3° at the concave fillets (structural: a concave arc's normals converge at its centre), classification of the benchmark background with both donor invariants. P0 MMS on these meshes (tests/cylinder_flag_mms.rs, exact acceptors, line-implicit): Stokes orders 2.17 / 2.13, upwind 2.00 / 1.86 (cell Péclet ≈ 0.1), divergence ≤ 9e-14 — the fillet skew costs nothing measurable. Rule: a refinement ladder's geometry must be fixed in physical units — with fillet = h/2 the Stokes orders read 1.74 → 1.31, the O(h) boundary perturbation masquerading as a scheme defect; the fillet is a parameter (5 mm across the ladder). Also: the P3b knock-outs H1/H2 on the balanced default (no effect), the P3 §5.10 record in the falsifier's header. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-05 19:50:14 -07:00
Omar SobhandClaude Fable 5.1	62df6bd628	rtx-cfd: overset P3b — the reclassification impulse located (the fringe ring is a staircase of the interpolated velocities' mass defect) and removed by a converged fringe flux balance (default on): falsifier max spike 594 → 5.50 N/m at the FSI2 step (staircase 6490), 10.95 / 16.79 at dt/2 / dt/4 (12600 / 25600), rms spike 0.07% of the force, far probe 6 (7900), KE per event 4.9e-3 J/m falling with Δt (2.6 fixed) ... OverlapMap::balance_fringe_fluxes: Gauss–Seidel through the prescribed faces of every fringe cell to 1e-12 of the prescribed flux scale (≤ 50 sweeps), after every fringe stamping (3 fixed sweeps 101 N/m, 10 sweeps 5.5 — converged is the rule). OversetParameters: fringe_flux_balance (default on, RTX_OVERSET_NO_BALANCE off), fringe_balance_tolerance, refill_turned_active (measured no effect: 593.7 → 593.8; kept as the record), stall_rounds opt-in. P3b locating trace RTX_OVERSET_TRACE_SP (continuity source by class change in cell volumes/step, stored-pressure jump of turned-active cells): the flipped cells' mass source ≤ 6e-3 cell volumes/step, their stored pressure 5–10% of the range off their neighbours (4.4% on the static MMS — the meshes' discretization disagreement). Knock-outs refuted (RTX_OVERSET_H1 keep own face velocities, H4 no warm start, pressure refill): 593–597 N/m each. S4 MMS with the balance: velocity errors within 0.1% of the pinned values, the background's overlap mass defect 1e-13 by construction, pressure errors unchanged. overset_mms prints pressure diagnostics; overset_falsifier records the balanced ladder (regression guard 20 N/m at dt; RTX_OVERSET_FALSIFIER_STRICT asserts the registered gates — (ii) holds at dt, misses at dt/2, dt/4; (iv) fails: residual ∝ 1/Δt^0.8). Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-05 19:16:16 -07:00
Omar SobhandClaude Fable 5.1	6b8837301f	rtx-cfd: overset Schwarz stall detection is opt-in (stall_rounds, default 0): right for a steady march (n=64: 2.26 rounds mean, no cap hits, L2 identical), wrong for a transient (falsifier max spike 594 → 4044 N/m when on); the MMS harness sets 2 ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-05 18:35:06 -07:00
Omar SobhandClaude Fable 5.1	e2edff9b1d	rtx-cfd: overset A-P3 — the falsifier plate on the overset (FAILS the registered gates by one order less than the staircase); wall force; composite pressure-level pin; Schwarz stall detection ... patch_gen::{stadium, graded_fractions}: the falsifier plate as a stadium O-grid (semicircular ends r = half-thickness; 16 cells per end arc, straights graded 0.30 h -> h at 1.15, offset 6 h, 12 rows stretched 4x; 148x12 cells, every ray a normal, worst non-orthogonality 4 deg). CurvilinearPisoSolver::surface_force (+ PatchLoad): F = sum(-p_f S_f + mu (grad u + grad u^T)_f . S_f) on the wall faces with the wall cell's LSQ gradients (wall Dirichlet in the velocity fit); HELD on the phantom circle against the exact stress integral: 1.3e-2 / 6.3e-3 / 3.6e-3 at n = 32/64/128 (orders 1.05 / 0.81), 22x the staircase's accuracy. OversetPisoSolver: the composite p' level pinned to zero mean over the active cells every round (the coupled problem is pure Neumann; the temporal warm start handed each step's level to the next — background pressure 1e7 growing 5e4 per step on the falsifier; an unpinned level also inflated the relative Schwarz stop); stall detection (no progress over three rounds = the inner solvers' noise floor; 6560 of 150k steps burned the 20-round cap at n = 64, a 7.5 h n = 128 march); schwarz_stalled in the result. tests/overset_falsifier.rs (records; RTX_OVERSET_FALSIFIER_STRICT asserts the registered gates, _LADDER runs dt/2 and dt/4, _TRACE the top-12 spike steps): max spike 594 / 981 / 1720 N/m at dt / dt/2 / dt/4 (staircase 6490 / 12600 / 25600), rms spike 61-89 (810), far probe 502-1509 (7900), KE injection 0.16-0.21 J/m per event on the common cell set (2.6) — every large spike a ~104-cell full-row reclassification; exponent -0.77 (-1.0). The registered 5% gate (8.75 N/m) is missed 68x: the overset's own reclassification impulse is the finding (omni-cortex overset_metal_campaign.md §5.10); P3b = locate per cell, then the fringe flux balance. tests/patch_stadium.rs, curvilinear_loads.rs, overset_common::plate_patch. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-05 04:32:43 -07:00
Omar SobhandClaude Fable 5.1	afd1bff6ee	rtx-cfd: overset A-P2 — the patch overlaps the background (OversetPisoSolver), gated S1–S5 ... Background = the embedded solver with a mask from the overlap classification (embedded/{mod,projection}.rs: module split, projection's solve/apply halves, set_overlap, fringe p' Dirichlet by elimination into extra_diag/rhs, anchor dropped, set_inner_stop_factor, phase API begin_step/solve_correction/ apply_correction/end_step; advance rebuilt on the phases — every suite digit- identical, FSI2 default line-for-line). Patch = the curvilinear solver with an acceptor ring (set_side_velocity; set_acceptor_ring/stamp_acceptors/ set_acceptor_correction; acceptor Dirichlet by elimination into PressureSystem.links so the BiCGSTAB stop stays in flux units — identity rows measured unconverged at 2431 iterations; same phase API). overset/overlap.rs: OverlapMap — hole/fringe/active from the patch's own indices (hole = body or k <= nn-1-overlap_rows, DEFAULT_OVERLAP_ROWS = 4 from the 2.9 h depth budget), dual-quad inverse-bilinear donors patch→fringe, lattice donors →acceptors, both invariants asserted, mass-defect measures. overset/mod.rs: OversetPisoSolver — advance (exchange rebuilt BEFORE the predictors from the previous corrected field), alternating Schwarz on the acceptor p' vector with Anderson(3) (plain Schwarz measured 0.82/round: floating patch, Neumann wall) and the previous step's vector as warm start (1 round/corrector at steady state), stop relative to the STEP's p' scale (the MG absolute stop is 1e-9/dt² in pressure — the whole second correction), set_patch_mesh, snapshot/restore carrying the warm-start vector. Gates: overlap linear-exact 1e-13, quadratic orders 1.96/1.99 (acceptors), 1.40/1.91 (fringe); half-couplings: patch with exact acceptors Stokes 2.07/1.98 + 2.08/1.98, upwind 0.84/0.84, background with exact fringe 7.86e-3/2.90e-3/ 1.09e-3 (1.44/1.41); two-mesh MMS n=32/64: background 8.717e-3/4.207e-3 (1.03x/ 0.97x the embedded circle), patch 1.322e-2/6.904e-3 (1.5-1.6x), orders 1.05/ 0.94, patch div <= 5e-13, overlap mass defect 3.6e-3 -> 8.2e-4 of the overlap flux (under the registered 1e-3 from n=64; disclosed at 32); motion: stationary patch through set_patch_mesh bit-identical, snapshot/restore with a pending mesh bit-identical, translating phantom circle 1.22x/1.19x the static level over 4.5 cells. Inherited, disclosed: poisson_equivalence's no-body multigrid pin fails by 3.9e-9 at d46fb0b (M1's commit; verified in a clean worktree). Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-04 19:24:13 -07:00
Omar SobhandClaude Fable 5.1	d46fb0b7a7	rtx-cfd: overset A-P1 GATED — the curvilinear patch moves and deforms under an exact 2-D DGCL ... StepGeometry (motion.rs): time-averaged face vectors S̄_f = ½(S^n + S^{n+1}) and swept volumes δV_f = S̄_f·δc_f — exact for linear node motion on any quad, so Σ sign δV_f = V^{n+1} − V^n is algebra (1.8e-14 measured; the EndOfStep control 2.1e-3). CurvilinearPisoSolver::set_mesh(next) names the end-of-step geometry; advance swaps it in, rebuilds operators + pressure matrix on it (L_f, LSQ gradients, no mesh-velocity term in the projection), keeps the old mesh for V^n and the explicit boundary data; predictor in the conservative ALE form V^{n+1} û = V^n u^n + dt(−Σ sign (F − δV/dt) u_f + ν D + f V^n), written as u·(V^n/V^{n+1}) + … so a stationary mesh is bitwise the static path; fluxes on S̄_f; snapshot carries both meshes; swept_face_rule knob (Trapezoidal default, EndOfStep = negative control). Stokes limit keeps the mesh flux (was dropped with convection) and centres it (upwinding it cost an order: 1.06/1.00). Gates (tests/curvilinear_ale.rs, 11 tests, 83 s): uniform flow on a wiggling AND bending annulus 4.44e-15 over 400 steps, p exactly 0, 0 pressure iterations; control deviates 4.9e-5; stationary mesh through the moving path bit-identical (both diffusion variants); snapshot/restore on the moving mesh bit-identical; Taylor–Green orders unchanged — upwind 0.995/0.976 vs fixed 0.987/0.975 at 1.05× error, Stokes 1.92/1.97 vs 1.94/1.99 at 2.4×, moving annulus 2.11/2.02; linear-field falsifier 1.95/1.92 (annulus), 1.91/1.43 (square, sliding wall nodes). P0 ladders re-run identical to every digit. Rule from the diagnosis: start a moving run ON the t = 0 mesh and sweep less than a cell per step — a first step that jumped 2–4 cells imprinted an O(displacement) error no refinement removed (dt- and motion-independent). Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-04 17:00:04 -07:00
Omar SobhandClaude Fable 5.1	c63d79c300	rtx-cfd/rtx-fsi: overset A-P0 GATED + M1 precision probe — curvilinear collocated PISO: relative-reduction pressure stop (the absolute stop floored |du/dt| at 2e-4 on 64²), line-implicit-n sign fix, adjustPhi; gates: Cartesian reduction 1.37–1.40x the staggered error at orders 0.83/0.90; skewed stretched periodic annulus Stokes orders 2.30/2.06 (explicit and line-implicit), upwind 1.08/0.80; Poiseuille exact to 1e-9 on Cartesian and affine-sheared periodic channels (both diffusion variants), varying-skew channel order 2.02 (v 1.9), cell mass 1e-14; divergence ≤ 1e-11 relative every step; snapshot/restore bit-identical. M1: poisson.rs multigrid hierarchy generic over MgScalar (f32/f64), f64 CG keeps its own fine level; MgPrecision on MultigridParameters/EmbeddedParameters/PisoParameters, set_poisson_precision, harness RTX_FSI2_POISSON_F32 (march + noise probe, printed marker); f64 arm bit-identical in vivo (FSI2 default line-for-line with 08-31), f32 arm holds the noise floor and stall pins and the FSI2 band; poisson_equivalence f32 arm ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-04 12:40:43 -07:00
Omar SobhandClaude Fable 5.1	52da75a3a9	rtx-cfd: curvilinear collocated PISO on a structured patch (overset A-P0, WIP) — PatchMesh (right-handed s,n; periodic seam with shift; face metrics), patch generators (TFI, skewed annulus, sheared/varying-skew channels), CSR + Jacobi-BiCGSTAB, the Zang–Street–Koseff incremental step with the node-based 9-point L_f, LSQ gradients, explicit and line-implicit-n predictors, adjustPhi; tests: mesh metrics (5 green), operators exact on linear fields incl. the seam (green), sparse (2 green), MMS ladder (Cartesian 16/32: 1.37–1.39x the staggered error, order 0.83; n=64 stalls at a |du/dt| floor 2e-4 — open, tolerance-scaling hypothesis), annulus/Poiseuille not yet run ... Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-04 05:00:08 -07:00
Omar SobhandClaude Fable 5.1	1347bc6772	test(rtx-cfd): fresh-cell falsifier — circle body, far-field probe, kinetic energy per step, speed knob, and the per-flip kinetic-energy split by face class (interior / fresh / dead) ... The split locates the flip's velocity change: 71% (plate) / 61% (circle) on the DEAD faces — fluid faces the wall reaches, overwritten with the wall-side reconstruction in one step (a ~0.25 U_b jump per face) — 27–38% in the interior response, ~1% on fresh faces. Five treatments leave the per-flip impulse/energy unchanged on this falsifier (all measured, none kept unless already committed): substeps, the swept-volume source (40x worse), the fresh-face field extension, face apertures + wall-relative divergence in the projection (-12%, and it breaks the static invariants), and imposing the t^{n+1} wall before the predictor. The impulse is intrinsic to a binary staircase wall that stands still between flips and jumps a cell; the record is in omni-cortex docs/fresh_cell_gcl_campaign.md. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-03 11:56:04 -07:00
Omar SobhandClaude Fable 5.1	c9492d3e1e	test(rtx-cfd): fresh-cell falsifier extended (circle body, far-field probe, kinetic energy, speed knob) + print-only divergence trace; two candidate fixes REFUTED on it (swept-volume source 40x worse at either sign; fresh-face field extension no effect), both kept default-off with their verdicts ... Phase 1 of omni-cortex docs/fresh_cell_gcl_campaign.md. The mechanism of the moving-body force spikes is measured from four directions: per-flip force amplitude ∝ 1/dt, kinetic energy injected per flipped cell 0.048 J/m independent of dt and body shape (plate row vs circle), felt at a far-field pressure probe, and ∝ U^2 (2.60 / 0.64 / 0.15 J/m at U = 1 / 0.5 / 0.25). A binary mask's wall position jumps by one cell at every flip and the fluid answers with a fixed impulse. Neither the swept-volume source (the wall faces already carry the swept volume — the source double-counts it) nor the fresh-face velocity is where it lives. Next: the virtual cut cell in the projection (apertures + the wall-relative divergence), registered in the campaign doc. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-03 11:40:28 -07:00
Omar SobhandClaude Fable 5.1	23eb996a9f	test(rtx-cfd): the fresh-cell falsifier — an oscillating flag-sized plate on the FSI2 grid and dt; force spikes track fresh cells (90% at dt) and their per-event amplitude scales as dt^-1.0 (rms dt^-0.44) ... Phase 0 of omni-cortex docs/fresh_cell_gcl_campaign.md (Seo & Mittal's oscillating-body test on this embedded solver). Plate 0.35 x 0.02 m, 1 m/s peak, 80 mm amplitude, still fluid, h = 1/152, dt = 3.24e-4 and its halvings; force sampled as the coupling samples it. Measured: at rest exactly zero; moving, 648 fresh cells per sweep at every dt, rms spike 810 / 1080 / 1490 N/m and MAX spike 6.5e3 / 1.26e4 / 2.56e4 at dt, dt/2, dt/4 — the per-event impulse doubles with each halving (a fixed whole-cell volume error per fresh cell delivered in one step, the raw (dV/dt)|1 - CFL_b| source), against a physical added-mass force of ~1.3e3. RTX_FRESHCELL_LADDER=1 runs the ladder, RTX_FRESHCELL_CSV=<dir> dumps per-step records. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-09-03 11:24:24 -07:00
Omar SobhandClaude Fable 5	bff84ccdcc	rtx-cfd: mask hysteresis — sticky cell classification against a reference mask ... The measured FSI3 killer is the bistable mask: one geometry (|d| identical to 4 digits) samples two load branches (60 vs 120 kN), and the traced s=1 death is the secant walking a 20x load cliff (68,886 -> 1,307,938 N over a 1e-3 candidate change). A sticky band makes the load map single-valued at the crossing: formerly-fluid cells flip only at phi < -band, formerly-solid at phi > band, classified against the mask held at rebuild time — in a coupling loop, the restored committed step-start mask. Band 0 is structurally bit-identical (phi > -0.0 <=> phi > 0.0) and verified digit-for-digit on both committed defaults (FSI2 and FSI3, every physics digit). Measured cost on the translating-circle MMS at band 0.25h: +0.5% field error (u/p ratios 1.17/2.12 vs the no-hysteresis moving levels 1.16/2.11); flip delay = band/(v dt), deterministic. Exposed as RTX_FSI{2,3}_HYST in multiples of h_min. Co-Authored-By: Claude Fable 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2	2026-08-26 15:27:09 -05:00
Omar SobhandClaude Fable 5	4534d90684	rtx-fea + rtx-cfd: the single-step seams FSI2 stands on ... rtx-fea: NonlinearDynamicAnalysis refactored onto a NonlinearDynamicStepper - set_nodal_forces on both (the interface load of a coupling subiteration, replaceable between steps and between subiterations of one step); - step(&DynamicState) is a pure function of the start-of-step state and the current forces - commits nothing, so a partitioned coupling re-runs one Newmark step to the interface fixed point (the piston semantics); - run() marches through the same stepper: one code path, pinned from both ends (linear limit, CSM3, and a new manual-drive == run() assertion); - new test: a nodal step load oscillates about the *static* nonlinear analysis's deflection (cross-code-path, mean within 3%, amplitude 6%), with re-run determinism and force-swap sensitivity asserted mid-march (a one-step response to a force change is ~ beta dt^2 - the first assertion draft demanded 10% and was corrected against the physics). rtx-cfd: the subiteration seam and the moving no-slip closure - EmbeddedPisoSolver::snapshot()/restore() (mask + time + init flag; the mask is now Clone): re-running a fluid step within a subiteration is bit-identical to never having diverted - proven on a moving body with cells flipping in the re-run window; - polygon_interface_velocity: nearest-edge linear interpolation of per-vertex velocities, exact for the linear-along-edge boundary data a finite-element interface hands over - the no-slip closure that replaces FSI1's zero-velocity polygon. Suites: rtx-fea 567, rtx-cfd 325, rtx-fsi piston+transfer - all green. Co-Authored-By: Claude Fable 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01Lnyrw33Lu6rUhW42E9KHwq	2026-08-20 20:00:49 -07:00
Omar SobhandClaude Fable 5	0ad31abb6b	rtx-cfd: F2 — the moving embedded body, and falsifier 3 measured ... EmbeddedPisoSolver::set_moving_body: the mask is rebuilt at the end-of-step geometry every step, and the new mask's ghost values are reconstructed FROM THE PREVIOUS CORRECTED FIELD (EmbeddedMask:: impose_from — the boundary-history principle extended to a moving wall), so a stationary body run through the moving path is bit-identical to the static path, which is the first test. A velocity face that flips solid -> fluid enters the new interval holding exactly the ghost reconstruction the previous step left on it — a consistent near-wall value, not garbage; a fresh pressure cell is refilled from its fluid neighbours before the predictor's gradient can read the value it kept while inside the body. The body must move under a cell per step (the convective dt limit already enforces this for bodies slower than the local peak velocity). EmbeddedResult reports fresh_cells. tests/embedded_moving.rs: - a stationary body through the moving path: 0.0 difference over 100 steps (and zero fresh cells, identical ghost corrections); - a circle (r = 0.2) translating through the steady manufactured field with the exact field as its surface velocity — the solution must hold still while the mask sweeps 84 cells fresh over 300 steps at n = 32: max L2 velocity error 9.85e-3 = 1.16x the static steady level (8.489e-3), max L2 pressure error 4.67e-2 = 2.11x the static level (2.22e-2), bulk |div u| 1.6e-7, projection residual 5.9e-9 every step. That pressure ratio is the geometry decision's falsifier 3 (omni-cortex docs/turek_hron_geometry_decision.md): fresh-cell transients sit at ~2x the static discretisation error, not orders above it — the falsifier does not fire and no cut cells are needed. Measurement note, recorded in the test: the divergence of body-adjacent cells read after the end-of-step ghost re-imposition is a one-step lag by design (the next projection honours the re-imposed prescribed fluxes — the same lag the static path has); the continuity claims are the projection residual and the bulk divergence over all-fluid-faced cells. Deferred: an oscillating-cylinder benchmark against published force histories (Duetsch et al. 1998) when the FSI rungs need it. rtx-cfd 321 -> 323 green. Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-20 13:07:28 -07:00
Omar SobhandClaude Fable 5	35b2b2cdf4	rtx-cfd: TVD convection in the embedded predictor — the wake sheds — and Turek–Hron CFD2/CFD3 ... First-order upwind's numerical viscosity |u| h / 2 is ~10x the physical viscosity on the Turek–Hron grids: the effective Reynolds number lands near 20 and CFD3 (Re 200) produced NO vortex shedding at all — one lift zero-crossing in three seconds at h = 10 mm. The physics, not a bug. EmbeddedParameters gains `convection_scheme` (default Upwind, bit- identical — the no-body degeneracy test still reads 0.0): the TVD branch adds SIMPLE's limited face corrections (van Albada / van Leer, `face_correction` now pub(crate)) directly in the explicit predictor — no deferred iteration needed in an explicit step. Domain-side faces and faces whose far-upwind node is outside fall back to upwind exactly as in SIMPLE; near the body the stencil reads ghost values, which encode the wall. Verified: the embedded-circle MMS error drops 10–16x below upwind (8.16e-4 vs 8.49e-3 at n = 32) at observed order 1.56 (SIMPLE's TVD measured 1.59–1.84). tests/turek_hron_cfd23.rs — CFD2 (Re 100, steady) and CFD3 (Re 200, periodic), both with the benchmark's inflow ramp, both measured as time statistics over a window (never a snapshot), surface route primary and the control volume printed as the diagnostic (its central-difference evaluation truncation grows with the convective flux: the routes agree to 0.6% at Re 20 and differ 15–25% at Re 100–200 on these grids). Measured across h = 10 / 6.6 / 5 mm: - CFD3 shedding frequency 4.2746 / 4.3400 / 4.3939 Hz vs the reference 4.3956 — converging −2.8% -> −1.3% -> −0.04%; - CFD3 lift mean −184 / +160 / −2.6 vs −11.9 — lands on the reference; lift amplitude ±438 / ±556 / ±557 vs ±437.8 — +27% at the finer grids, unconverged (the flag is 2/3/4 cells thick); - CFD2 control-volume drag 152.4 / 143.3 / 139.4 vs 136.700 — +2.0% at 5 mm; CFD2 surface drag sits ~−10% (the boundary layer is ~one cell); CFD2 lift −3.4 / +30.2 / +8.4 vs 10.53. Suite defaults run CFD2 at ny = 62 and CFD3 at ny = 41 (cost); the asserted bands are the measured ones (frequency 10%, mean drag 15%, amplitude 35%), not accuracy claims; RTX_CFD2_NY / RTX_CFD3_NY run the studies. Also recorded: the CFD1 refinement study extended to h = 3.3 mm (RTX_CFD1_NY): control-volume drag 14.8996 (+4.25%), apparent order ~0.70 sustained over four grids, control-volume lift 1.1332 vs 1.11905 (+1.3%). rtx-cfd 318 -> 321 green (full suite 321 passed / 0 failed). Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-20 11:37:04 -07:00
Omar SobhandClaude Fable 5	327da7ff47	rtx-cfd: multigrid-PCG projection — 30x faster, same answers — and the CFD1 refinement study ... Falsifier 4 of the Turek–Hron geometry decision fired (the SOR projection cost 0.09 s/step at 250x41 and an hour per run at 5 mm); this answers it. solvers::incompressible::poisson: PoissonProblem (cell-centred five-point SPD operator as per-cell face coefficients + Dirichlet diagonal extra + active mask) and solve_multigrid_pcg — conjugate gradient preconditioned by one V-cycle of geometric multigrid: aggregation by 2 per direction (odd sizes absorbed, coarse cell active iff any child is), the Galerkin coarse operator for piecewise-constant prolongation / summation restriction, symmetric Gauss–Seidel smoothing, coarse correction scaled by 2 (Braess's under-correction of unsmoothed aggregation; scalar, so the preconditioner stays symmetric and positive on range(A)), L1 TRUE-residual stop with a stagnation guard. Singular systems are handled per connected component of the active cells (mean projection and level per pure-Neumann component; the anchor's component to p[anchor] = 0). PoissonSolverKind::{Sor, Multigrid} on PisoParameters / EmbeddedParameters; Sor is the default and its code is byte-for-byte untouched; an unconverged multigrid solve falls back to the SOR sweeps for that projection. Verified (poisson/tests.rs, tests/poisson_equivalence.rs): - PCG iterations to cut the residual 1e-8 on the closed Neumann box at 32^2..256^2: 4, 4, 4, 4; ragged masked domains 8/8/8; - manufactured recoveries to ~1e-14; Galerkin identity A_c v = R A P v to 7e-15 on every level (masked, outlet column, non-uniform conductances); V-cycle symmetric to 1e-14; NaN-poisoned inactive cells untouched; - two Neumann components with opposite imbalances, and a Dirichlet component beside an imbalanced Neumann one (review scenarios): converge, each component right up to its own constant; - speed vs plain SOR at the same stop: 22.7x (128^2), 41x (256^2); - same answers as SOR: PISO MMS 4.6e-8 relative, Taylor–Green divergence 1.4e-9 every step, embedded-circle MMS 7e-8, no-body bit-identity with MG on both solvers, channel+outlet+circle 1.4e-10; CFD1 loads identical to four digits at 0.003 s/step vs 0.094 (30x). CFD1 refinement study (tests/turek_hron_cfd.rs, three grids, 257 s): h = 10 / 6.6 / 5 mm -> control-volume drag 15.6156 / 15.2829 / 15.0988 vs 14.2929 (+9.25 / +6.93 / +5.64%), apparent order 0.71, Richardson extrapolate 14.04; surface route and lift not monotone (flag 2/3/4 cells thick) — the test asserts the measured band at the finest grid. Built with a 4-agent workflow (core, integration, refinement study, adversarial review); the review found no defects and four risks, three fixed here (per-component projection, one symmetric smoother-sweep parameter, acting on `converged` with an SOR fallback) and one recorded (isotropic aggregation loses grid-independence on anisotropic cells). rtx-cfd 301 -> 318 green. Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-20 10:20:25 -07:00
Omar SobhandClaude Fable 5	c25f15b3c4	rtx-cfd + rtx-fea: embedded-boundary PISO and total-Lagrangian SVK — the first two Turek–Hron rungs ... The Turek–Hron geometry decision (omni-cortex docs/turek_hron_geometry_decision.md) chose an embedded boundary on the fixed Cartesian MAC grid over body-fitted unstructured ALE; this commit builds the first rung on each side of the ladder, verified MMS-first. rtx-cfd — solvers::incompressible::{embedded, embedded_body}: EmbeddedPisoSolver is the fixed-grid PISO predictor/projection with per-side domain boundaries (ALE's SideBoundary semantics, so the channel has an outlet), a (x, y, t) boundary-velocity function, and an optional EmbeddedBody (signed distance + surface velocity; circle / rectangle / union). EmbeddedMask classifies cells (fluid iff phi > 0 at the centre) and faces (fluid iff both cells fluid; ghost within 1.5 h; solid deeper); the predictor updates fluid faces only, the projection enforces continuity on fluid cells with zero coefficient across prescribed faces, ghost faces are re-imposed after each projection from a boundary-intercept least-squares linear fit (exact for linear fields), the net ghost mass flux is removed uniformly so a Neumann projection stays compatible, and loads come by two routes: surface-stress reconstruction (full viscous traction) and a control-volume momentum balance. Verified (tests/embedded_mms.rs, tests/turek_hron_cfd.rs): - no body, closed box: bit-identical to PisoSolver over 200 steps; - embedded off-centre circle MMS 16/32/64: velocity orders 0.92, 0.97 (plain PISO 0.85, 0.91), pressure 0.96, 0.90, max |div u| <= 9e-8 on every fluid cell, compatibility correction 6e-4 -> 3e-5; force on the circle vs the exact surface integral: surface route 0.52 -> 0.29 -> 0.15, control-volume route 0.61 -> 0.30 -> 0.15 (both first order, two unrelated readings of the same solution); - Turek–Hron CFD1 (Re 20, h = 10 mm, flag two cells thick), settled to four digits: surface drag 15.71 / lift 0.94, control-volume drag 15.62 / lift 1.08 vs reference 14.29 / 1.119 — the drag routes agree to 0.6%, both +9.5%. A coarse first number; the refinement study waits on a multigrid projection (SOR: 0.1 s/step at 250x41 in the test profile). Fourteenth defect of the campaign: the fixed-grid PISO predictor zeroes the transverse convective face velocity on its domain sides (exact for walls); carried into a solver with an outlet it dropped the OUTGOING momentum flux through the outlet side of the v control volumes, the last column accumulated, and CFD1 went NaN at t ~ 4 s. Found by printing where max |u| lived (x = 2.5) after halving dt changed nothing. Fluxes now come from the stored boundary faces on every side. rtx-fea — elements::total_lagrangian + NonlinearStaticAnalysis:: with_total_lagrangian(): Green–Lagrange strain, second Piola–Kirchhoff stress from a St. Venant–Kirchhoff law on the material's Lamé parameters (plane strain in 2-D), B_L of the current deformation, material plus geometric tangent; dead-load body force per reference volume. Verified (tests/total_lagrangian_svk.rs): - zero displacement: the plane-strain stiffness to 1e-13; - tangent = d f_int/du by central differences at 20% random displacement (Quad4, Quad8, Hex8): relative < 1e-7, symmetric to 1e-12; - a 34-degree rigid rotation produces no internal force; the small-strain routine does (negative control); - manufactured finite-strain solution, body force by FD of the exact P = F S: Quad4 orders 1.95, 1.98; Quad8 2.93, 3.03, 3.02 (an 8% amplitude, Green–Lagrange strain to -0.25 near SVK's compressive limit E = -1/3, broke Newton on fine meshes — the material, not the code; 3% is clean); - Turek–Hron CSM1 at 70x4 Quad8: u(A) = (-7.060, -65.43) mm vs (-7.188, -66.10), 1.0% / 1.8%, converging from below (35x2: -65.14); CSM2: (-0.4604, -16.79) vs (-0.4690, -16.97), 1.1% / 1.8%. rtx-cfd 293 -> 301 green (5 unit + 3 integration), rtx-fea 559 -> 564. Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-20 08:51:32 -07:00
Omar SobhandClaude Fable 5	4bd98b5264	rtx-cfd + rtx-fsi: the added-mass piston — partitioned FSI on the real ALE fluid ... The first coupled fluid-structure computation in the workspace, verified against a closed form, and the first time rtx-fsi's added-mass claims run against a real discretised fluid rather than a linear model map. ALE extensions: per-side boundaries (Velocity / SlipWall / PressureOutlet) and moving boundary lines. A moving Velocity side is a material wall whose prescribed normal velocity must equal the line's own motion; a pressure outlet takes Dirichlet p' = 0 in the projection (replacing the Neumann anchor) with a zero-gradient predictor on its faces. Fluid half verified alone (tests/ale_piston_channel.rs): prescribed piston motion, slip walls, outlet. The incompressible rigid column is exact DISCRETELY - continuity forces every u to the wall's discrete velocity (8e-12) and the projected pressure is exactly linear with gradient rho times the wall's backward-difference acceleration (2.5e-9). Coupled benchmark (rtx-fsi/tests/piston_added_mass.rs): elastic piston (Newmark average acceleration) against added mass rho*L*H at mass ratio 6.25, rtx-fsi's Subiterated driving a real fluid/structure pass per step: - plain staggered diverges in 7 subiterations (Causin-Gerbeau-Nobile on a real solver); - Aitken converges at 3.0 subiterations/step onto T = 1.07009 vs the closed form 1.06999 - 9.8e-5 relative, halving with dt; - outlet flux matches the piston sweep to ~1e-9 every step. Discrete-analysis finding: Newmark beta scales the staggered added-mass threshold - the iteration gain is beta*m_a/(M + K*beta*dt^2), so the continuous ratio 2.5 CONVERGES at beta = 1/4 (gain 0.625, measured ~17 passes/step) and the benchmark needs ratio 6.25 (gain 1.56). Two real defects found and fixed, twelfth and thirteenth of the campaign: 1. rtx-cfd ale::advance re-stamped boundary faces at t_old from the current boundary function, which in a coupling loop carries the NEW interval's wall velocity - the predictor's old state had interior u = w0 but wall face u = w1, leaving an O(dt) pressure artifact confined to the wall-adjacent cells (p exact to 6e-11 everywhere except the wall cell at 4.7e-5). The start-of-step boundary faces are whatever the previous step's end-of-step application left there. 2. rtx-fsi aitken_factor guarded its denominator - a SQUARED residual- difference norm - against a bare f64::EPSILON, silently disabling Aitken below residual ~1e-8 and degrading to unit relaxation exactly in the well-converged regime; the repulsive fixed point then amplified 1e-9 residuals back up and the coupling diverged. Third instance of the absolute-threshold species (NNLS, ECSW). The guard is relative now; aitken_is_scale_invariant pins it at initial residual 1e-9. rtx-cfd 293 green (+1), rtx-fsi 29 green (+3). rtx-fsi's lib gains only the relative guard; the coupling layer still depends on no solver (rtx-cfd is a dev-dependency of its tests). Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-20 06:10:13 -07:00
Omar SobhandClaude Fable 5	259c5baa63	rtx-cfd: ALE on a moving tensor-product grid, DGCL-exact by construction ... The first brick of the Turek-Hron frontier: PISO (explicit conservative predictor + SOR projection) generalised to a staggered grid whose x- and y-lines move arbitrarily each step while the domain boundary stays fixed. The discretisation choice that carries everything: time-averaged face areas (A^n + A^{n+1})/2 in both the fluid fluxes and the face-swept volumes. For tensor-product motion the discrete geometric conservation law then holds as an algebraic identity, so uniform flow is a machine-precision fixed point, not a truncation-order one: - DGCL test: uniform (0.7, -0.4) on a 16x12 grid with interior lines wiggling out of phase, 400 steps: max deviation 7.9e-15 (~35 ulp). Negative control with end-of-step areas (per-step cell error exactly dw*dh/V, the cross term the identity absorbs): 1.5e-2 - a 1e12 separation, so the test can fail. - Degeneracy: zero motion on a uniform grid vs fixed-grid PISO over Taylor-Green steps: max difference 2.2e-16 - one ulp - pinning every geometric generalisation to the verified implementation. - Physics under motion: Taylor-Green on the wiggling mesh, L2 error 2.42e-2 -> 1.07e-2 (n=16 -> 32, order 1.17); moving-mesh error at n=32 sits below the fixed-mesh 1.1532e-2 (PISO's published value to four digits); energy decay unchanged by the motion. One trap documented in the test: the projection's inner-stop floor (0.1 * tolerance * reference_flux) at an engineering tolerance lets a one-sweep partial p' accumulate into p, whose gradient perturbs the velocities at ~1e-11 with the geometry blameless. The DGCL run must use a rounding-level tolerance because machine-precision preservation is the claim under test. Measured: 3.6e-11 at tol 1e-9, 7.9e-15 at 1e-13. Incompressibility needs no mesh-velocity term: subtracting the GCL from moving-cell mass conservation leaves plain div(u) = 0 on the current geometry, so the projection is the fixed-grid one with non-uniform coefficients. 292 rtx-cfd tests green (288 + 4). Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-20 05:31:12 -07:00
Omar SobhandClaude Fable 5	b321a9aba7	rtx-cfd: Taylor-Green validates PISO's transient path — and fixes the projection's inner solve ... With k = pi the decaying Taylor-Green vortex has zero normal velocity on the unit box for all time, so it fits the closed staggered domain exactly, with ZERO body force: convection is balanced identically by the true TG pressure and the decay comes from viscosity alone. This exercises exactly what the steady MMS harness cannot see — the time derivative, the unsteady pressure coupling and the projection's splitting error. The time-decaying tangential wall velocity enters by re-setting the wall hook each step. Measured (16/32/64, dt ~ h^2): L2 velocity 2.267e-2, 1.153e-2, 5.841e-3 — orders 0.97 and 0.98, first-order upwind's rate — and the kinetic-energy deficit against the exact e^(-4 nu pi^2 T) halves per refinement (0.0690, 0.0360, 0.0185; ratios 1.92, 1.95), within 2.3% on the finest mesh. Every step divergence-free to ~1e-7. Its first run caught two defects in the projection's inner solver: - The inner Gauss-Seidel stop summed the per-sweep iterate CHANGE — the same movement-not-residual pseudo-criterion the SIMPLE census flagged: slow modes move little per sweep while their residual is still large. - Plain GS contracts smooth modes by only 1 - O(h^2) per sweep, so the 400-sweep cap left max |div u| ~ 1e-2, GROWING with mesh size (8e-3 at 16^2 to 2e-2 at 64^2). The inner stop now measures the true equation residual, the sweep is SOR at the optimal Poisson factor omega = 2/(1 + sin(pi h)), and it converges relative to each projection's own source with a floor tied to the outer mass tolerance — so a long steady march no longer burns a hundred sweeps per step polishing negligible corrections. The steady MMS harness had masked all of this: a march to steady state iterates the projection to death regardless, which is why its divergence read 1e-9 while a 205-step transient left 1e-2. mms_piso's steady-state criterion is 1e-6 (was 1e-7): per-step projection noise at the mass tolerance floors |du/dt| just below 1e-6, and the L2 errors under measurement are 1e-2 to 1e-3. Its results are unchanged to six figures and still match SIMPLE's. 288 rtx-cfd tests, 0 failing. Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-20 00:35:06 -07:00
Omar SobhandClaude Fable 5	d8a30db155	rtx-cfd: Ghia Re=400 as a quantitative claim — and the stopping-tolerance trap ... The Re=400 lid-driven cavity, 128^2 TVD on an exactly-unit domain, sampled on the staggered faces that lie exactly on the centrelines, against Ghia, Ghia & Shin (1982) — reference values sourced from two independent transcriptions that agree digit for digit (Mramor/Vertnik/Sarler CMC 2013 Table 1, and the ivan-pi benchmark collection): u_min -0.32667 at y = 0.2852 (Ghia: -0.32726 at 0.2813 — 0.18%) v_min -0.45024 at x = 0.8633 (Ghia: -0.44993 at 0.8594 — 0.07%) v_max 0.30044 at x = 0.2305 (Ghia: 0.30203 at 0.2266 — 0.53%) max |u - Ghia| over 15 profile stations: 0.0051 Ghia's own values carry ~0.3% discretisation error (Sahin & Owens 2003 put u_min at -0.32838), so this is at the reference's own accuracy. The finding worth the commit message: the first run used the Re=100 test's residual tolerance of 1e-4 and read u_min = -0.31987 — "converged", 2.3% shy — and refining to 192^2 made it WORSE (-0.30879, profile deviation doubled from 0.034 to 0.074). The residual had dropped below tolerance while the field was still developing, and the effect grows with mesh size because SIMPLE's per-iteration contraction weakens as h -> 0: at fixed residual tolerance the finer mesh stops at an EARLIER stage of convergence. Tightening the stop (3e-5, then 1.5e-5, until the movement per halving fell below the reference's own error) was the fix, and the test's bands are set so the premature-stop state fails all of them. "The residual converged" must never stand in for "the answer stopped moving". Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-19 23:23:32 -07:00
Omar SobhandClaude Fable 5	e94ad1be6b	rtx-cfd: Poiseuille closed-form validation with exact-zero assertions ... Plane channel driven by a uniform body force: u(y) = G/(2mu) y(1-y), v = 0, p exactly constant. Convection vanishes identically, so this isolates diffusion, the half-cell wall treatment and the pressure coupling — and two of the three answers are exact zeros, which no benchmark comparison offers. The ends are clamped to the profile the DISCRETISATION prefers — the 1-D tridiagonal with half-cell wall closures, solved directly in the test — rather than to the continuous parabola. That makes (u_hat, 0, const) an exact fixed point of the 2-D discretisation, and the solver must sit on it: |u - u_hat| ~ 1e-10, max |v| ~ 1e-10, p spread ~ 8e-10 (16^2) A first version clamped the ends to the continuous parabola instead; the O(h^2) incompatibility between that profile and the discrete one drove a weak secondary flow near the ends (max |v| = 1.3e-3) — a property of the mismatched boundary data, not of the solver, recorded in the test docs so nobody rediscovers it as a bug. The wall treatment's own truncation is measured in isolation as |u_hat - parabola|: 3.906e-3 at 16, 9.766e-4 at 32 — refinement ratio exactly 4.00, second order, in closed form c h^2 / 4. Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-19 19:32:37 -07:00
Omar SobhandClaude Fable 5	9b097fca0d	rtx-cfd: PISO validated by manufactured solution — after fixing the inverted projection ... PisoSolver was the only major solver in the workspace with no verification of any kind. Writing the MMS harness for it (tests/mms_piso.rs) and inspecting the implementation found the census's defect species again: - The pressure correction had its SIGN inverted: it solved -lap(p') = +rho div(u*)/dt and then corrected with u = u* - (dt/rho) grad(p'), so each projection DOUBLED the divergence instead of removing it. - The momentum sweeps froze the near-wall lines (1..ny-1) and the pressure correction skipped the outer ring of cells (1..nx-1) — both exactly the defects repaired in SIMPLE. - The "explicit" predictor read neighbours the same sweep had already overwritten, so the step depended on sweep order. - The pressure gradient was dropped entirely on the last interior face. Rewritten as a genuinely explicit predictor plus anchored-Neumann projection on the staggered grid, with the conventions SIMPLE now embodies: near-wall lines are unknowns with half-cell wall diffusion, continuity on every cell, boundary faces are prescribed data. Momentum-source and wall-velocity hooks added so the manufactured solution can reach it. Measured (16 -> 32 -> 64): L2 velocity 3.516214e-2, 1.953750e-2, 1.037512e-2 — orders 0.85 and 0.91, first-order upwind's rate — with max |div u| ~ 1e-9 in every cell. The errors agree with SIMPLE's on the same meshes to six or seven significant figures: an implicit under-relaxed outer iteration and an explicit time-marching projection land on the same discrete steady solution, which is what sharing a spatial discretisation must produce and is very hard for two independently wrong solvers to fake. 285 tests, 0 failing. Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-19 19:28:39 -07:00
Omar SobhandClaude Fable 5	796cf173e6	rtx-cfd: second-order convection by deferred-correction TVD; MMS order 1.84, cavity closes on Ghia ... First-order upwind's O(h) numerical viscosity was the measured limit on the whole discretisation: MMS order ~0.9 at Re = 20 against 2.05 in the Stokes limit. This adds a ConvectionScheme parameter to SimPLE — Upwind (default, behaviour unchanged), TvdVanAlbada, TvdVanLeer — implemented by deferred correction: the upwind operator stays implicit, so a_p = sum(a_nb) and diagonal dominance survive unconditionally, and the limited high-order-minus-upwind flux difference enters the source explicitly at the current iterate. At a fixed point the two agree, so the converged answer is the TVD discretisation. Faces whose far-upwind node lies outside the domain fall back to pure upwind; wall faces pass no mass, so no correction enters. Measured by the manufactured solution (van Albada, 16 -> 32 -> 64): L2 velocity 1.325e-3 4.406e-4 1.232e-4 orders 1.59, 1.84 (upwind) 3.516e-2 1.954e-2 1.038e-2 orders 0.85, 0.91 The error is 27x to 84x below upwind's at equal resolution, the order climbs toward 2 (the shortfall is limiter clipping plus the boundary fallback, both of which shrink with h), the pressure error falls at the same rate, and continuity still holds to solver tolerance in every cell. On the Re = 100 lid-driven cavity at 65^2 the centreline minimum moves from -0.1932 (upwind) to -0.2036 against Ghia's -0.2109 — 59% of the remaining gap closed at equal resolution, converged in 790 iterations — and the vortex position moves from 0.5000 to 0.4844 toward Ghia's 0.4531. Both new cavity bounds exclude the upwind values, so falling back to first order fails them. 284 tests, 0 failing. Co-Authored-By: Claude Fable 5 <[email protected]>	2026-08-19 19:16:48 -07:00
Omar SobhandClaude Opus 5	1a740e0b2c	rtx-cfd: the wall treatment is second order, not first — correct the record ... The manufactured-solution test carried a hypothesis for why the observed order sits below 1: that `(u_P - u_wall)/(dy/2)` approximates the wall gradient at y = dy/4 rather than at the wall, making the near-wall rows first order. Measuring in the Stokes limit refutes it. With convection negligible every remaining operator is second order, so the observed rate there reports the wall treatment directly: rho = 1.000 (Re = 20.00) 3.52e-2 1.95e-2 1.04e-2 orders 0.85 0.91 rho = 0.001 (Re = 0.02) 2.21e-3 5.35e-4 1.28e-4 orders 2.05 2.06 2.05 and 2.06. The half-cell wall term is second-order accurate and the Stokes discretisation reaches its nominal rate. The shortfall at Re = 20 is first-order upwind and nothing else, which is what a first-order convection scheme is supposed to give. Comment corrected rather than left standing: a plausible explanation that happens to be wrong is worse than none, because it sends the next person to fix something that is not broken. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>	2026-08-19 17:42:14 -07:00