astronomix.data_classes.simulation_helper_data module

Geometric helper data for the simulation.

Bundles the precomputed per-cell geometry (cell centers, radii, volumes, cell boundaries) used throughout the solver and the snapshot diagnostics, together with the machinery to build only the fields the active subsystems actually need (see HelperDataRequirements), optionally on the host, and to pad / shard / unpad them for the time integrator.

class astronomix.data_classes.simulation_helper_data.HelperData(geometric_centers: Array = None, volumetric_centers: Array = None, cell_centers_x: Array = None, cell_centers_y: Array = None, cell_centers_z: Array = None, r: Array = None, r_hat_alpha: Array = None, cell_volumes: Array = None, inner_cell_boundaries: Array = None, outer_cell_boundaries: Array = None)

Bases: NamedTuple

Helper data used throughout the simulation.

cell_centers_x: Array

1D arrays of cell centers along each Cartesian axis. Shape (N_axis + 2 * ngc,). These broadcast against the state array so consumers that only need one axis (e.g. the frame tracker) avoid materialising the full meshgrid.

cell_centers_y: Array

Alias for field number 3

cell_centers_z: Array

Alias for field number 4

cell_volumes: Array

The cell volumes.

geometric_centers: Array

The geometric centers of the cells. For Cartesian dimensionality > 1 this is the full meshgrid of cell coordinates with shape (Nx, Ny[, Nz], dim). Subsystems that only need a single axis should prefer cell_centers_x / cell_centers_y / cell_centers_z so the full meshgrid does not need to be materialised.

inner_cell_boundaries: Array

Coordinates of the inner cell boundaries.

outer_cell_boundaries: Array

Coordinates of the outer cell boundaries.

r: Array

cell center to box center distances only for config.dimensionality > 1

r_hat_alpha: Array

A helper variable, defined as hat{r}^alpha = V_j / (2 * alpha * pi * Delta r) with V_j the volume of cell j, alpha the geometry factor and Delta r the cell width.

volumetric_centers: Array

The volumetric centers of the cells. Same as the geometric centers for Cartesian geometry.

class astronomix.data_classes.simulation_helper_data.HelperDataRequirements(needs_geometric_centers: bool = False, needs_volumetric_centers: bool = False, needs_cell_centers_x: bool = False, needs_cell_centers_y: bool = False, needs_cell_centers_z: bool = False, needs_r: bool = False, needs_r_hat_alpha: bool = False, needs_cell_volumes: bool = False, needs_inner_cell_boundaries: bool = False, needs_outer_cell_boundaries: bool = False)

Bases: NamedTuple

Per-field requirements for HelperData.

Each flag indicates whether the matching HelperData field is consumed by any active subsystem (solver, physics module, snapshot calculator). Fields whose flag is False are left unmaterialised and stay at the HelperData default of None.

needs_cell_centers_x: bool

Alias for field number 2

needs_cell_centers_y: bool

Alias for field number 3

needs_cell_centers_z: bool

Alias for field number 4

needs_cell_volumes: bool

Alias for field number 7

needs_geometric_centers: bool

Alias for field number 0

needs_inner_cell_boundaries: bool

Alias for field number 8

needs_outer_cell_boundaries: bool

Alias for field number 9

needs_r: bool

Alias for field number 5

needs_r_hat_alpha: bool

Alias for field number 6

needs_volumetric_centers: bool

Alias for field number 1

astronomix.data_classes.simulation_helper_data.get_helper_data(config: SimulationConfig, sharding: None | NamedSharding = None, padded: bool = False, requirements: None | HelperDataRequirements = None) → HelperData

Generate the helper data for the simulation.

Only the fields requested by requirements are materialised; the rest stay at the HelperData default of None. When requirements is None (the default), all fields are built so that scripts using get_helper_data to construct initial conditions keep working. The time integrator passes a config-derived HelperDataRequirements explicitly so the in-simulation helper data is minimal.

With config.host_helper_data=True the arrays are built inside a CPU device context and only the requested fields are moved onto the target device (respecting sharding for 3D Cartesian geometric_centers). Fields needed only as intermediates (e.g. the full X, Y, Z meshgrid when only r is requested) never materialise on the accelerator.