pyPolyMesh

A Python library to read, write, and modify OpenFOAM polyMesh meshes in memory. It focuses on mesh topology and geometry: boundary inspection, connectivity builders, in-place mesh edits, scaling, and diagnostics for manually specified cyclic patch pairs.

Detailed guides live under docs/.

Features

• Read and write ASCII or binary constant/polyMesh (points, faces, owner, neighbour, boundary)
• Query mesh topology via PolyMesh (cells, faces, boundaries, adjacency)
• Build compact cell–face and cell–point connectivity arrays
• Compute geometrial properties (face areas and centroids)
• Modify meshes in place (merge cells, boundary edits, point scaling, and more)
• Diagnostics (currently only checking of cyclic/periodic patch pairs)(diagnostics)

Requirements

• Python 3.8+
• NumPy, Numba
• transformations (cyclic diagnostics)

Installation

Clone the repository and install from the project root:

pip install .

Editable install while developing:

pip install -e .

Quick start

Point PolyMesh at a case directory (the folder that contains constant/polyMesh):

from pypolymesh import PolyMesh

# Can read and auto-detect both binary and ascii, by default expects int32 and float64
mesh = PolyMesh("path/to/case")

# Display some information - many intuitive methods under PolyMeesh class
print(mesh.n_points, mesh.n_cells, mesh.n_faces, mesh.n_boundaries)
print(list(mesh.boundary.keys())[:5])

# Inspect one boundary patch
patch = "inlet"
print(mesh.boundary[patch])
face_ids = mesh.boundary_faces(patch)
print("first face points:", mesh.face_points(face_ids[0]))

# Scale coordinates (topology arrays are unchanged)
mesh.scale((0.001, 0.001, 0.001))  # mm -> m, for example

# Write mesh back under a new case path in ASCII Format
mesh.write("path/to/output_case", mode="ascii")

See Getting started for dtypes, verbosity, and write options.

Documentation

Guide	Description
Getting started	Install, load/save, core properties
Connectivity and geometry	Cell–face/point lists, areas, ordered VTK-style points
Mesh modification	Edits, scaling, current vs original indices
Diagnostics	Cyclic / periodic patch pair checks
Visualization	Plotly primitives (in development)

API details are also available in module and class docstrings.

Development

Run tests from the repository root:

python -m unittest discover -s tests -v

Status and limitations

• Mesh modification features are experimental
• The pypolymesh.visualization package is under active development and is not yet a supported end-user plotting API.