2 Commits

Include renames

Author	SHA1	Message	Date
Omar SobhandClaude Opus 5.5	5572fd12fb	Merge r8e-coupled-dt-stability (R8-e: the coupled 3D FSI dt instability = the harness's structure-to-fluid mapping, fix RTX_E3FSI_KIN=surface; default-off). Merge fixes with R8-h: the surface station list over stations() (the flat tip's station A = the mean of the tip corners); the impulse test's capsule-only flat_tip(). Merged-tree gate (r6/merge_gate7): slab default / check / all-host / plate byte-identical to main's base, suites 2/2 3/3, the default coupled smoke = R8-a's march row for row, a KIN=surface + TIP=flat + LOADS_DEVICE coupled run clean ... Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>	2026-09-26 05:02:51 -05:00
Omar SobhandClaude Opus 5.5	74fac32a91	R8-e: the coupled 3D FSI's small-dt instability located in the load/kinematics transfer, not a lagged fluid response ... - tests/fsi2_embedded3_impulse.rs (new, ignored, cuda): the added-mass timing instrument — the R8-a fluid with a prescribed centreline velocity step (a one-step acceleration delta), baseline and impulse passes from one device snapshot, the load difference per step. Pitch shape on the slab ny 62: generalized added mass 39.11 / 39.09 / 39.07 kg/m at dt x 1 / 0.75 / 0.5, the step after carries 1.7 / 1.3 / 0.9 % above the steady tail — the cut-cell fluid answers in the same step (the lagged-added-mass hypothesis refuted). - fsi2_embedded3.rs: `RTX_E3FSI_LINE_CSV` (per-step centreline + mid/bottom/top y per station) showed the growing 2dt mode is a through-thickness mode — the edge nodes move against the mid-plane nodes (~4:1): the fluid reads the mid-plane, the loads land on the edges, so the added mass acts on that mode with the wrong sign (a negative effective added mass; the scalar Newmark model is unstable for it at omega dt below ~1-2 with gamma 0.7, stable at larger dt or gamma 0.9 — R8-a's observed pattern). `RTX_E3FSI_KIN=surface` (default off, byte-identical when unset): the fluid's centreline = the mean of the bottom and top edge nodes (the nodes the loads land on) — dt x 0.75 / 0.5 / 0.25 stable at gamma 0.7. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>	2026-09-25 22:11:31 -05:00