# 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

$$
\nabla p = -\partial_t \mathbf{u} - (\mathbf{u}\cdot\nabla)\mathbf{u}
           + \nu \nabla^2\mathbf{u}.
$$

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.