metadata/schema.md

HDF5 schema

Each data/<split>/<case_id>.h5 file is a self-contained trajectory. N varies by trajectory; T=601 throughout.

Dataset	Shape	Dtype	Meaning
uvp	[T, N, 3]	float32	Channels [u, v, p]
time	[T]	float64	Dimensionless public time, 0:0.1:60
points	[N, 2]	float32	Graph-node coordinates
cells	[F, 3]	int32	Triangular connectivity
boundary	[N]	uint8	0=interior, 2=inlet/farfield ramp, 3=outlet, 4=obstacle wall
data	[1, N, 3610]	float32	Legacy DGN-compatible packed tensor; prefer the explicit datasets above
diagnostics/compact_iterations	[T]	uint64	OpenLB compact-stream iteration identity
diagnostics/inlet_ramp_scale	[T]	float64	Applied fifth-order ramp scale
diagnostics/lbm_density	[T, N]	float32	Sampled LBM density
diagnostics/physical_time	[T]	float64	Solver physical time
diagnostics/openlb_sampling_points	[N, 2]	float32	OpenLB sampling coordinates
diagnostics/nearest_material	[N]	uint8	Nearest OpenLB material code
diagnostics/*residual	[T]	float64	Pressure/streamfunction recovery diagnostics

Important root attributes include the accepted case identity, geometry family, split, Reynolds number, solver spacings, pressure semantics, contour identities, and sanitized source-code identities represented in metadata/cases.jsonl.

Pressure semantics

p is density-normalized specific pressure recovered from the unsteady Navier--Stokes relation

$$\mathrm{\nabla }p=-{\mathrm{\partial }}_t\mathbf{u}-(\mathbf{u}\cdot \mathrm{\nabla })\mathbf{u}+\nu {\mathrm{\nabla }}^2\mathbf{u}\mathrm{.}\backslash nabla\; p\; =\; -\backslash partial\_t\; \backslash mathbf\{u\}\; -\; (\backslash mathbf\{u\}\backslash cdot\backslash nabla)\backslash mathbf\{u\}\; +\; \backslash nu\; \backslash nabla^2\backslash mathbf\{u\}.$$

The supplied fluid-triangle topology is used and the right outlet is the exact zero-pressure gauge. It is not a direct raw OpenLB pressure field.