code/DATASET.md

Parametric rotating-cube CFD dataset

Generated with OpenFOAM ESI v2512 (pimpleFoam, AMI dynamic mesh, laminar) per the LOCKED design in CLAUDE.md. Reproduces/extends the phi-GNN 3D rotating-cube case (Gao, Cheng, Jaiman) as a 2D parameter sweep for a downstream neural operator.

Grid (25 cases, complete)

• Re ∈ {50, 100, 150, 200, 300} — varied by viscosity only (nu = 1/Re).
• psi ∈ {0, 15, 30, 45, 60}° — inflow elevation out of x-y plane, U_inf = (cos psi, 0, sin psi); azimuth beta = 0 fixed.
• Constant across all cases: U_inf|=1, c=1, physical omega=0.25 rad/s (omega*=0.25), dt*=5e-3, sampling every 8 steps (dt*_sample=0.04), endTime t*=200.

Storage layout (per case runs/Re{Re}_psi{psi}/)

• Decomposed across 12 processors (scotch). U and p only are written per snapshot (writeObjects FO); the rigid-rotation mesh is stored once in processor*/constant/polyMesh (+ rotating cellZone). Reconstruct node positions downstream from theta = omega * t on the rotating zone; U is absolute-frame.
• 4991 snapshots/case over t* = 0..200 (binary). 58 GB/case, **1.4 TB total**.

Force coefficients — stationary average over t* ∈ [150, 200] (~1250 samples)

Aref = c² = 1, magUInf = 1, dragDir = (1,0,0), liftDir = (0,1,0); Cs = axial (z) force. *_std = RMS fluctuation about the mean (vortex-shedding amplitude).

Re \ psi	0°	15°	30°	45°	60°
Cd
50	2.334	2.270	2.094	1.790	1.321
100	1.718	1.690	1.620	1.428	1.038
150	1.513	1.497	1.407	1.289	0.916
200	1.423	1.413	1.307	1.075	0.843
300	1.358	1.354	1.297	1.096	0.641
Cl (Magnus, from +z spin)
50	-0.287	-0.288	-0.282	-0.240	-0.160
100	-0.337	-0.345	-0.358	-0.292	-0.190
150	-0.381	-0.369	-0.392	-0.328	-0.198
200	-0.404	-0.350	-0.345	-0.315	-0.196
300	-0.407	-0.323	-0.302	-0.272	-0.242
Cs (axial force)
50	0.000	-0.653	-1.163	-1.535	-1.811
100	0.000	-0.503	-0.844	-1.109	-1.308
150	0.000	-0.463	-0.824	-0.991	-1.155
200	0.000	-0.450	-0.827	-1.087	-1.095
300	0.000	-0.430	-0.816	-1.032	-1.149
Cd_std (shedding amplitude)
50	0.129	0.115	0.085	0.049	0.020
100	0.153	0.139	0.116	0.073	0.032
150	0.163	0.150	0.133	0.086	0.040
200	0.168	0.157	0.136	0.089	0.043
300	0.165	0.185	0.136	0.092	0.037

Physics check (both axes carry distinct physics — as designed)

• Cd ↓ with Re (drag crisis trend) and Cd ↓ with psi (cross-flow component cos psi shrinks as inflow tilts toward the spin axis).
• Cs grows with psi from 0 → ~-1.8 — the genuine axial through-flow force that has no in-plane analogue; this is the new physics psi was chosen to span.
• Shedding amplitude (Cd_std) shrinks with psi — oblique/axial inflow suppresses the 2D vortex street — and grows with Re. psi=0 columns are the classic 2D shedding limit.
• Cl < 0 everywhere: Magnus-type lift from the fixed +z rotation sense.

Laminar-validity note (for dataset docs)

The no-turbulence-model (laminar) assumption is most strained at the high-Re / low-psi corner (Re=300, psi=0–15), where shedding fluctuation peaks (Cd_std ≈ 0.16–0.19) and oblique rotation is least stabilising. These cases ran stably to t*=200 with bounded Courant, but treat Re=300 (esp. psi ≤ 15) as the resolution/validity ceiling of the current mesh; increasing psi monotonically stabilises the wake (Cd_std → 0.04 at psi=60).

Validation provenance

• Phase 1 (static cube, low-blockage): Cd = 0.978 vs paper 0.935, bracket [0.854, 1.122] — PASS.
• Phase 2 (rotating AMI mechanics): AMI weights 1.0→1.0002, continuity ~1e-13, ~0.6 s/step/12-core.