| name | gmsh-sim |
| description | Use when driving Gmsh (finite-element mesh generator) via .geo DSL scripts or Python scripts using the gmsh API — 2D/3D meshing, CAD import, boundary layers, export to downstream solvers (CalculiX, OpenFOAM, FEniCS, SU2) through sim runtime one-shot execution. |
gmsh-sim
You are connected to Gmsh via sim-cli. This file is the index —
see the sections below for content.
Gmsh is an open-source finite-element mesh generator. It is a
pre-processor (not a solver). Its "result" is a mesh file (.msh)
that feeds downstream solvers like CalculiX, OpenFOAM, FEniCS, SU2.
Two input forms:
.geo — Gmsh native DSL (SetFactory, Point, Sphere, Physical Volume, ...).py — Python scripts that import gmsh and call the API
Both are run by sim via subprocess. .geo goes through Gmsh's CLI
wrapper; .py runs as plain Python (the script itself does
gmsh.initialize() / .finalize()).
base/ — always relevant
| Path | What's there |
|---|
base/reference/geo_scripting.md | GEO kernel DSL basics: Point/Line/Circle/Surface/Volume, Physical groups, OpenCASCADE. |
base/reference/python_api.md | gmsh Python API patterns (initialize/add/occ/synchronize/mesh.generate/write). |
base/reference/mesh_formats.md | .msh v2 vs v4 format, export targets for downstream solvers. |
base/snippets/01_sphere_mesh.geo | Verified unit-sphere mesh snippet. |
base/known_issues.md | Shebang on PATH, pip wheel vs system binary, msh2 vs msh4. |
solver/4.15/ — Gmsh 4.15 specifics
solver/4.15/notes.md — provenance, capabilities, format defaults.
Hard constraints
- Gmsh is a mesher, not a solver. Acceptance = mesh topology
(node/element count, bbox, physical-group tags), NOT physical state.
- Always define Physical groups when the mesh feeds a downstream
solver — untagged entities are NOT exported by default.
- OpenCASCADE kernel requires
synchronize() before meshing or
querying entities, after any boolean/create operation.
- Default output format is MSH 4.1; many downstream solvers need
MSH 2.2 (
-format msh22 flag).
- Never confuse
Mesh.<option> = ... (config) with geometry
commands — a .geo containing only options has no geometry to mesh.
Required protocol
After sim check gmsh confirms availability: gather Category A inputs
from user (geometry intent, target mesh size, physical group semantics,
downstream solver format). Write .geo or .py. Lint with sim lint.
Run with sim run --solver gmsh. Validate via JSON output from script
(node/element counts, bbox). Hand off .msh to downstream solver driver.
