The Enzo Hierarchy File - Explanation and Usage¶
The Enzo Hierarchy file is a representation of the internal memory state of the entire hierarchy of grids. As such, its format – while somewhat obtuse at first – reflects that context. Each grid entry has a set number of fields that describe its position in space, as well as the fields that are affiliated with that grid:
Grid = 1 Task = 4 GridRank = 3 GridDimension = 38 22 22 GridStartIndex = 3 3 3 GridEndIndex = 34 18 18 GridLeftEdge = 0 0 0 GridRightEdge = 1 0.5 0.5 Time = 646.75066015177 SubgridsAreStatic = 0 NumberOfBaryonFields = 8 FieldType = 0 1 4 5 6 19 20 21 BaryonFileName = ./RD0005/RedshiftOutput0005.cpu0000 CourantSafetyNumber = 0.300000 PPMFlatteningParameter = 0 PPMDiffusionParameter = 0 PPMSteepeningParameter = 0 NumberOfParticles = 20 ParticleFileName = ./RD0005/RedshiftOutput0005.cpu0000 GravityBoundaryType = 0 Pointer: Grid->NextGridThisLevel = 2
The final field, starting with “Pointer”, is slightly more complicated and will be discussed below.
Grid = 1
This is the ID of the grid. Enzo grids are indexed internally starting at 1.
Task = 3
This grid was written by processor 3 and will be read in by it if restarting more than 4 processors.
GridRank = 3
This is the dimensionality of the grid.
GridDimension = 38 22 22
Dimensions, including ghost zones.
GridStartIndex = 3 3 3
The first index of data values owned by this grid.
GridEndIndex = 34 18 18
The final index owned by this grid. The active zones have dimensionality of GridEndIndex - GridStartIndex + 1.
GridLeftEdge = 0 0 0
In code units, between DomainLeftEdge and DomainRightEdge, the origin of this grid.
GridRightEdge = 1 0.5 0.5
In code units, between DomainLeftEdge and DomainRightEdge, the right-edge of this grid. dx = (GridRightEdge - GridLeftEdge)/(GridEndIndex - GridStartIndex + 1).
Time = 646.75066015177
The current time to which the baryon values in this grid have been evolved.
SubgridsAreStatic = 0
Whether refinement can occur in the subgrids.
NumberOfBaryonFields = 8
The number of data fields associated with this grid.
FieldType = 0 1 4 5 6 19 20 21
The integer identifiers of each field, in order, inside this grid.
BaryonFileName = ./RD0005/RedshiftOutput0005.cpu0000
The HDF5 file in which the baryons fields are stored.
CourantSafetyNumber = 0.300000
Courant safety number for this grid (governs timestepping.)
PPMFlatteningParameter = 0
Flattening parameter for this grid (governs PPM hydro.)
PPMDiffusionParameter = 0
Diffusion parameter for this grid (governs PPM hydro.)
PPMSteepeningParameter = 0
Steepening parameter for this grid (governs PPM hydro.)
NumberOfParticles = 20
How many particles are located in this grid at this timestep.
ParticleFileName = ./RD0005/RedshiftOutput0005.cpu0000
The HDF5 file in which the baryon fields and particle data are stored. This field will not exist if there aren’t any particles in the grid.
GravityBoundaryType = 0
Boundary type inside gravity solver.