SU2#

.su2 read + write eager

Summary of the specification#

The SU2 native mesh is plain ASCII, keyed by uppercase tokens on their own lines. NDIME= gives the dimension, NELEM= precedes the volume element list - one line per element: a VTK element type code, its node indices, then the element index - and NPOIN= precedes the coordinates. Boundaries are declared per marker: NMARK= counts them, then each MARKER_TAG= names one and MARKER_ELEMS= lists its surface elements in the same code-then-nodes form.

Specification at a glance#

dimension	NDIME= 2 or 3
elements	NELEM= then <vtk_type> <nodes…> <index>
type codes	3 line, 5 triangle, 9 quad, 10 tetra, 12 hexa, 13 prism, 14 pyramid
points	NPOIN= then coordinates, one point per line
boundaries	NMARK=, MARKER_TAG=<name>, MARKER_ELEMS=<n>

Read the full SU2 specification ↗

Reading#

import polyxios as px

mesh = px.read("model.su2")
mesh.vertices          # (n, 3)
mesh.element_types     # element groups found in the file

Writing#

px.write(mesh, "out.su2")

This codec takes no format-specific options.

Quirks worth knowing#

Boundary marker names become element tags, so named inlets, outlets and walls survive a round trip.
A 2-D file’s coordinates are padded with a zero z, so the mesh is 3-D like every other one polyxios holds, and global_attrs["was_2d"] records the fact. NDIME follows it: a flagged flat mesh, or any mesh with no z extent, goes out as 2. A mesh whose vertices have since left it is written in three with a warning.
The trailing per-element index is read but not trusted for ordering; elements keep file order.