of2su2 — OpenFOAM mesh → SU2 mesh

Converts an OpenFOAM mesh (constant/polyMesh, including snappyHexMesh meshes with polyhedra and hanging nodes) into a valid, conformal SU2 mesh, and reports its quality exactly as SU2 computes it.

• Single file, Python 3 + numpy. No OpenFOAM or SU2 installation needed.
• Only what SU2 cannot use is changed: hex, prism, pyramid and tet cells are written as they are; polyhedra and hanging-node cells are split into standard elements, mostly without added points.
• Checked output: no inverted elements, every face matched, Σ volume = domain volume, SU2's own dual-CV quality.
• Nothing dropped silently: zones, interfaces, patch types and groups are carried over or listed.

Installation

pip install of2su2                                          # from PyPI
pip install git+https://github.com/VaibhavHiwale/of2su2     # latest version from GitHub
of2su2 --help

Or download the single file of2su2.py and run python3 of2su2.py (needs only numpy).

Usage

# convert (case folder or its constant/polyMesh folder)
of2su2  path/to/openfoamCase  mesh.su2

# convert and improve the worst added points against SU2's quality metrics (slower)
of2su2  path/to/openfoamCase  mesh.su2  --opt-apex 40 --opt-vr 1000

# score any .su2 file with SU2's quality metrics (optionally compare with SU2's MESH_QUALITY output)
of2su2  --check mesh.su2  [--vtk flow.vtk]

Output: mesh.su2, a full report mesh.su2.json, mesh information mesh.su2.info.json, and a summary on screen:

zone rotating: 42,404 points, 61,106 elements, markers blade_wall, blade_root_cap, blade_tip_cap, AMI1
  valid: YES (non-positive elements 0, unmatched faces 0)
  SU2 orthogonality min 15.0° (points < 20°: 8, < 25°: 35), CV face AR max 173, sub-volume ratio max 357
  SU2 orientation check (as SU2 v8.5.0 does it): flips 0, distorted 0; boundary quads flips 0, distorted 2
zone rest: 13,092 points, 18,902 elements, markers farfield, AMI2
  ...
interface rotating | rest: markers AMI1 / AMI2 (coupled patches (cyclicAMI))
NOT carried over: pointZone 'frozenPoints' (0 points): the SU2 mesh format has no point sets

Options

What it handles

Names are kept and made SU2-safe where needed; every rename is listed.

Multizone meshes and --tri-interface

For a rotating zone (MRF) in SU2, separate the zone in OpenFOAM first:

createBaffles -overwrite                 # faceZone → patch pair (e.g. cyclicAMI AMI1/AMI2)
mergeOrSplitBaffles -split -overwrite    # duplicate the points → two separated cell regions
of2su2 . mesh.su2             # → 2 SU2 zones, interface markers AMI1/AMI2

In the SU2 config use MARKER_ZONE_INTERFACE= ( AMI1, AMI2 ) and KIND_INTERPOLATION. The interface nodes coincide, so NEAREST_NEIGHBOR is exact. SU2's conservative WEIGHTED_AVERAGE interpolation fails (NaN) on quadrilateral interface elements; --tri-interface triangulates every interface face identically on both sides and splits only the cells touching the interface (tets on the interface, pyramids elsewhere). It is the only option that changes cells SU2 could use as they are.

Known limitations

• 3D meshes only; periodic cyclic patches with a transform are not converted.
• Validated on the bundled test meshes and on one large snappyHexMesh rotor mesh (13.7 M cells, MRF zone, conformal and baffled); other meshers may show cell types not covered yet — the validity check reports any failure.
• Large meshes need memory (≈ 31 GB for 13.7 M cells) and time (≈ 7 min; ≈ 40 min with --tri-interface).
• At zone interfaces each SU2 zone sees only half of a node's control volume, so SU2's orthogonality there is lower than for the same mesh as one zone. This comes from SU2's dual mesh, not from the conversion.

Method and validation

See docs/METHOD.md: SU2 mesh requirements (from the SU2 source), the conversion steps, the quality metrics, performance, validation results and credits.

Tests

pip install pytest && python3 -m pytest -q tests/

Licence

GPL v3 or later (LICENSE). of2su2 contains the hanging-node transition-pattern table of MixedOcTree (github.com/clobosmesher/MixedOcTree, (C) 2013-2017 Claudio Lobos et al., GPL v3), based on E. González & C. Lobos, "A set of mixed-element transition patterns for adaptive 3D meshing" (2014/15). Other prior art is credited in docs/METHOD.md.

Citation

If you use of2su2 in published work, please cite it (GitHub: "Cite this repository", from CITATION.cff).