From 8ce810cc99d78ef46451cade99dcd12dd851c5e7 Mon Sep 17 00:00:00 2001 From: Claude Date: Fri, 30 Oct 2026 10:28:24 +0000 Subject: [PATCH] =?UTF-8?q?docs:=20D=C3=BCtsch=20Re100/KC5=20prescribed-os?= =?UTF-8?q?cillation=20protocol=20draft?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Co-Authored-By: Claude Opus 5.5 --- docs/validation/duetsch_re100_kc5_protocol.md | 72 +++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 docs/validation/duetsch_re100_kc5_protocol.md diff --git a/docs/validation/duetsch_re100_kc5_protocol.md b/docs/validation/duetsch_re100_kc5_protocol.md new file mode 100644 index 0000000..848d57b --- /dev/null +++ b/docs/validation/duetsch_re100_kc5_protocol.md @@ -0,0 +1,72 @@ +# Prescribed in-line oscillation: Dütsch Re 100 / KC 5 — PROTOCOL DRAFT (not frozen) + +Production under test: `claude/moving-bodies-s3a` at `653fd997` (unchanged). +Primary source: Dütsch, Durst, Becker & Lienhart, J. Fluid Mech. 360, 249–271 +(1998), doi:10.1017/S002211209800860X. Items marked ⟨verify⟩ must be taken from +the paper itself (Grok) before freezing; nothing here is read from plots. + +## Criteria (kept separate) + +- Same-grid frame consistency (G4, frozen 2%): already evaluated; not reused here. +- Cross-resolution criterion: every reported observable's error against the + reference, and the fine-pair difference, must decrease monotonically over the + resolution ladder. No numeric grid threshold and no order label is added. +- Reference agreement: only against values with provenance (section 6). + +## 1. Kinematics + +- In-line only: `x(t) = -A sin(2 pi t / T)`, `u(t) = -U_max cos(2 pi t / T)` + ⟨verify sign and phase origin⟩; `KC = U_max T / D = 2 pi A / D = 5`, + `Re = U_max D / nu = 100`, so `A = 5 D / (2 pi)`. +- Prescribed per step through `set_body(offset, vx)` + `run(1)`, offset and + velocity evaluated analytically at step n (no differencing). +- Start: the paper's motion from rest ⟨verify Dütsch start⟩. Measured window: + whole cycles 4–6, fixed now, never shortened afterwards. A one-cycle smooth + ramp is a separately named variant that only checks start independence. + +## 2. Resolution ladder (uniform only, fixed Mach) + +| D (cells) | U_max | nu_lat | tau | steps / period | +|---|---|---|---|---| +| 20 | .04 | .008 | .524 | 2,500 | +| 40 | .04 | .016 | .548 | 5,000 | +| 80 | .04 | .032 | .596 | 10,000 | + +- MRT collision (SRT at tau ≈ .524 is the recorded unstable regime). +- Mach check: U_max .02 vs .04 at D = 40 (separate, labelled). + +## 3. Domain and boundaries + +- Square still-fluid box, default 40 D; domain check 20 D vs 40 D at D = 40 + ⟨verify Dütsch domain extent⟩. +- Boundary family declared by the runner owner before running (x-periodic / + y free-slip or closed walls, whatever the dense runner supports without + production change); swept band ±A + R + 2 clear of any seam. +- Per-step displacement ≤ .04 cells (bound .5). + +## 4. Observables (raw, per step, preserved) + +- `obs` Fx, Fy (CME) and the diagnostics columns (`MovingTables.DIAG`): + CME, CME + Wen, CME + cover − uncover reported separately; crossings, + eq_only, no_donor. +- Velocity u, v on lines at the paper's x-stations relative to the mean + cylinder position and at its phase angles ⟨verify stations and phases⟩; + cell-centred values, documented bilinear interpolation in physical units. + +## 5. Metrics + +- Morison C_D, C_M by least squares over the measured cycles with the paper's + force definition and sign ⟨verify formula⟩; per-cycle RMS force; force + phase history; phase-resolved velocity profiles. +- Unit map for each candidate stated with `k = rho dx^3 / dt^2` per span. + +## 6. Reference data provenance + +- Accepted: values from the paper's tables, or digitized figure curves with + figure number, tool and uncertainty recorded. Curves without provenance are + qualitative only. Values quoted by later papers are secondary until checked. + +## 7. Order + +Protocol review → test driver (no production change) → runs → physical +validation verdict → only then single-cylinder VIV. No AMR, no pinball.