2 Commits

Include renames

Author	SHA1	Message	Date
Omar SobhandClaude Fable 5	c1bcdc408e	rtx-fsi: FSI3 floor 6e-5 — the floor rides with the motion; measure it through the cycle ... The first subcycle-2 study (t = 4 -> 8) ran 2.2 s of cycle — over [5, 6] s: +-42.8 mm at 6.2 Hz, trending toward the reference +-34.9 mm at 5.46 Hz from above — then stalled at t = 6.18 s: residual 1.9e-4 against an accept window of 1.5e-4 (5 x the 3e-5 floor the rest-state probe suggested), at a turning point of the cycle where the step increment, and with it the increment-relative part of the window, collapses while the flip noise does not. Floor set from the cycle's measured stall level (window 3e-4). Default re-verified: 581 steps, 3.5 subit/step (max 5), 0 stalls, conservation 1.5e-12, ux -2.90 +- 2.93 mm vs reference -2.86 +- 2.70. Co-Authored-By: Claude Fable 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01Lnyrw33Lu6rUhW42E9KHwq	2026-08-23 23:41:02 -05:00
Omar SobhandClaude Fable 5	c0666bf22a	rtx-fsi: C3 — FSI3 opened: the added-mass regime, its impulse artefact, and the coupler hygiene it demanded ... The march is extracted from the FSI2 test into a shared tests/fsi2_harness/march.rs (MarchConfig from env / MarchResult / window statistics), the harness parameterised by BenchmarkCase (FSI2, FSI3: inflow, solid density, modulus, rigid-flag drag reference), and turek_hron_fsi3.rs written on top (Re 200, density ratio 1, E 5.6e6). The committed FSI2 default is bit-identical through all of it — every new knob defaults to FSI2's behaviour; re-verified twice to every printed digit (uy 3.7732 / 3.7920 mm). FSI3's first contact, traced pass by pass (RTX_FSI3_TRACE), exposed the added-mass instability in its purest form and, one measured mechanism at a time, what a partitioned coupling at unit density ratio needs: - C^1 interface motion (MarchConfig::c1_interface): a constant per-step interface velocity is a velocity JUMP at each step start, and the incompressible fluid answers with an impulsive added-mass load ~ rho L dv / dt_fluid (8x the physical reaction under subcycling): 1,600 N at release, 48,000 N and a 59 mm response one step later, the flag's Newton dead the pass after. Constant acceleration from the previous end velocity to 2 dd/dt - v_n removes the impulse (loads 1,700-2,400 N). - IQN first-pass relaxation as a knob (initial_relaxation, FSI3 0.05): |1 - omega (1 + g)| must contract; 0.5 diverges past gain 3. - The divergence verdict waits for the secant (IqnIls): the exploratory second pass on a high-gain map legitimately overshoots 10x before the first secant column exists. Pinned by a gain-40 model test. - Kinematic predictor (predictor: "kinematic", velocity only): the structure-alone predictor ignores an added mass comparable to the flag's and overshoots 2-5x, drawing 5-6x loads every first pass; and NOT with the acceleration — Newmark average acceleration carries an inconsistent initial acceleration as a sign-alternating mode (d + dt v + dt^2 a / 2 predicted 22 mm at release; converged 0.14). - Quiescent release (quiescent_release): the structure-alone "consistent" initial acceleration M^-1 F ignores the added mass. - Coupler hygiene (IqnIls): a stalled or diverged step's secant columns are no longer retained (a bistable mask flip's columns extrapolated a 30 mm interface jump on the next step); two-window stagnation detection reports a plateau early instead of bouncing to the budget (a single-window test misjudged a slowly converging step and is recorded as such); trust region tightened to 10x the residual. A noise-column filter at the tolerance was measured to HURT (stalled a converging step at 5.5e-4) and is disabled (threshold 0). - The floor measured, not borrowed (fsi2_interface_noise.rs gains RTX_NOISE_CASE=fsi3): flip jumps 3.6e-4 (12x FSI2's), the subcycle-8 release map stalling near 1e-6, the subcycle-2 map converging to 9e-10; and through the release transient (flag at ~0.3 m/s) the subcycle-8 floor rides up to ~1e-3 with the motion — which moved the FSI3 default to subcycle 2 at a 3e-5 floor. FSI3 committed default (ny 62, release t = 4, t_end 4.2, subcycle 2): 581 steps, 3.8 subit/step (max 8), 0 stalls, 0 retries, conservation 4.3e-13; uy 10.1 +- 27.5 mm and ux -3.1 +- 3.2 mm over the first 0.2 s (reference cycle 1.45 +- 34.90, -2.86 +- 2.70). Machinery invariants pinned; physics bands await the study record. Rigid-flag drag 426.9 vs CFD3's 439.45 (-2.9%). The FSI2 mode-2 study pin (IQN / subcycle 2, t_end >= 16) was measured with the pre-hygiene coupler; re-verify on the next s = 2 study run. 48 lib tests green, clippy clean. Co-Authored-By: Claude Fable 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01Lnyrw33Lu6rUhW42E9KHwq	2026-08-23 19:43:02 -05:00