Tecplot SZL (.szplt)

Tecplot's subzone-loadable format, the default output of Tecplot 360 since 2016 and of TecIO-based solvers (SU2, FUN3D…). It is undocumented, and TecIO, Tecplot's own library, is its only reader, so meshio++ reads it through a TecIO the user already has. New in v16.13.0, read-only.

Format name	szplt
Extensions	.szplt (also found by content, #!SZPLT)
Read / Write	✓ / — (read-only)
Time steps	✓ — as Tecplot: the distinct solution times
Extra dependencies	TecIO: a core built with MESHIOPLUSPLUS_WITH_TECIO=ON, or a shared TecIO named by MESHIOPLUSPLUS_TECIO_LIBRARY

Reading

import meshioplusplus

mesh = meshioplusplus.read("flow.szplt")
last = meshioplusplus.read("flow.szplt", time_step=-1)
meshioplusplus.szplt.time_values("flow.szplt")

A .szplt reads exactly as the same data saved as .plt or .dat does: TecIO's reader fills the zone model the ASCII and binary Tecplot readers share, so zones, regions, point and cell data, variable sharing, passive variables, shared connectivity and time steps follow Tecplot. FEPOLYGON and FEPOLYHEDRON zones are refused by name (save such a file as .plt).

Getting TecIO

meshio++ never redistributes TecIO. Two ways to point it at yours:

• A native build with -DMESHIOPLUSPLUS_WITH_TECIO=ON -DTECIO_ROOT=<dir>, where <dir> holds TECIO.h (with tecio_Exports.h and StandardIntegralTypes.h) and libtecio — a static libtecio.a also needs pthread, which the build adds. This is what the C, Fortran, Julia and R bindings and the native CLI read through. TecIO is the source Tecplot distributes on its TecIO page (free, a registration form), or the copy a Tecplot 360 install carries; build/configure.sh --with-tecio <dir> sets both flags.
• The Python reader loads a shared TecIO through ctypes: set MESHIOPLUSPLUS_TECIO_LIBRARY to its path (Tecplot 360 ships libtecio.so / tecio.dll in its bin directory), or have it on the library search path. TecIO's own CMake builds a static library with hidden symbols; for a shared one, build it with add_library(tecio SHARED …) and without -fvisibility=hidden.

Without either, reading raises an ImportError naming both and the third way: save the file as .plt in Tecplot (Tecplot route).

Validation

The fixtures (tests/python/meshes/szplt) are written by TecIO 2018.3 — the TecIO source SU2 vendors — each beside an ASCII twin holding the same data: two FE zones of tetrahedra and bricks with cell-centred data, an ordered zone, a transient file sharing variables and connectivity with passive variables, and single-precision triangles. Both engines read every .szplt identically to its twin. A .szplt written by Tecplot 360 itself is listed in the roadmap.