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Supported Formats

Format Table

Format Read Write Extension Split
HDF5 yes yes .h5, .hdf5 no
Plot3D grid yes yes .x, .xyz no (grid only)
Plot3D solution yes -- .q no (flow only)
Tecplot ASCII yes yes .dat no
Tecplot binary yes yes .plt no (requires pytecplot)
Fortran unformatted binary yes yes -- low-level I/O
Raw binary (+ header) yes yes .s8 yes -- requires grid file

HDF5

Grouped layout with /grid and /flow groups. Supports single and multi-timestep layouts. Root-level attributes store scalar metadata (Mach, Re, etc.).

Plot3D

Standard NASA Plot3D structured grid format. Binary (Fortran unformatted) and ASCII variants are auto-detected. 2-D and 3-D grids supported.

Tecplot

ASCII .dat files in both POINT and BLOCK data packing. Binary .plt files require the pytecplot package (pip install cfd-io[tecplot]).

Raw Binary

Split formats store grid and flow data in separate headerless binary files. A companion header file provides the grid dimensions, variable names, and timestep indices.