foam2dolfinx

foam2dolfinx converts OpenFOAM output files into dolfinx meshes, meshtags, and functions for use in DOLFINx-based finite element workflows.

Note

This package was inspired by Stefano Riva's ROSE-pyforce repository.

Installation

conda create -n foam2dolfinx-env
conda activate foam2dolfinx-env
conda install -c conda-forge fenics-dolfinx mpich pyvista
pip install foam2dolfinx

Note

Only single cell-type meshes are supported. Supported VTK cell types: 10 (tetrahedron) and 12 (hexahedron).

Usage

Reading field data

Cell-centred data (e.g. from a finite volume solution) and point data are both supported:

from foam2dolfinx import OpenFOAMReader

reader = OpenFOAMReader(filename="my_case.foam", cell_type=12)

# Cell data — maps to a DG-0 function space
T_cells = reader.create_dolfinx_function_with_cell_data(t=1.0, name="T")

# Point data — maps to a CG-1 function space
U_points = reader.create_dolfinx_function_with_point_data(t=1.0, name="U")

Multi-domain cases

For multi-region OpenFOAM cases, pass the subdomain name to read fields from a specific region:

reader = OpenFOAMReader(filename="my_case.foam", cell_type=12)

T_fluid = reader.create_dolfinx_function_with_cell_data(t=1.0, name="T", subdomain="fluid")
T_solid = reader.create_dolfinx_function_with_cell_data(t=1.0, name="T", subdomain="solid")

Meshtags

Boundary patches and cell zones can be extracted as dolfinx.mesh.MeshTags for use in variational forms and boundary condition assignment.

For multi-domain cases, a single merged global mesh is built automatically. Interface facets between subdomains are detected and tagged with sequential IDs continuing after the boundary patch IDs.

from mpi4py import MPI
from dolfinx.io import XDMFFile
from foam2dolfinx import OpenFOAMReader

reader = OpenFOAMReader(filename="my_case.foam", cell_type=12)

facet_tags = reader.create_facet_meshtags()
cell_tags  = reader.create_cell_meshtags()

mesh = reader.dolfinx_meshes_dict["_global"]  # single-domain: use "default"

with XDMFFile(MPI.COMM_WORLD, "facet_meshtags.xdmf", "w") as f:
    f.write_mesh(mesh)
    f.write_meshtags(facet_tags, mesh.geometry)

with XDMFFile(MPI.COMM_WORLD, "cell_meshtags.xdmf", "w") as f:
    f.write_mesh(mesh)
    f.write_meshtags(cell_tags, mesh.geometry)

Both methods print a summary to stdout showing each patch/zone name, its assigned integer ID, and how many facets or cells carry that tag.

Finding available time values

reader = OpenFOAMReader(filename="my_case.foam", cell_type=12)
print(reader.times)  # e.g. [0.0, 0.5, 1.0, 2.0]

To find the closest available time to a target value:

from foam2dolfinx import find_closest_value

t = find_closest_value(reader.times, 1.3)  # returns 1.0 or 2.0