Troubleshooting

Floating point exception crash

Symptom: Python crashes with a SIGFPE when importing numpy or pandas after OpenFOAM initialization.

Cause: OpenFOAM enables floating point exception trapping (sigFpe). numpy triggers FPE during initialization (e.g., testing for denormals).

Fix: pyOFTools patches this automatically via pyOFTools.patch_pybfoam, which is imported by the test conftest. If you’re using pybFoam directly without pyOFTools, disable FPE manually:

import pyOFTools.patch_pybfoam  # import before numpy

“cannot find file controlDict”

Symptom: FOAM FATAL ERROR: cannot find file "./system/controlDict"

Cause: The Python script is not running from the case directory, or Time(".", ".") is called from the wrong working directory.

Fix: Ensure you cd to the case directory before running, or use absolute paths.

“field not found” or “no object registered”

Symptom: KeyError or OpenFOAM error when accessing a field.

Cause: The field hasn’t been read into the registry yet.

Fix: Call volScalarField.read_field(mesh, "fieldName") before using field(mesh, "fieldName"). In-situ post-processing (via pyPostProcessing) has fields available automatically because the solver reads them.

CSV files not created

Symptom: No files appear in postProcessing/.

Possible causes:

  1. ``pyFileName`` or ``pyClassName`` wrong in controlDict — check that the module and object names match your Python file.

  2. Python file not on sys.path — the file must be in the case directory (where you run the solver from).

  3. Write control — if using writeControl: writeTime, files are only written at OpenFOAM write intervals.

CSV files empty or corrupted in parallel

Symptom: CSV has duplicate rows or garbled content in parallel runs.

Cause: An older version of pyOFTools didn’t guard file writes by MPI rank. All ranks wrote to the same file.

Fix: Update to the latest pyOFTools. The TableWriter now only writes on the master rank (Pstream.master()). The aggregation results are globally reduced, so the master has the correct values.

OpenFOAM not found

Symptom: ImportError when importing pybFoam, or build fails with “OpenFOAM not found”.

Fix: Source the OpenFOAM environment before installing or running:

source /opt/openfoam2406/etc/bashrc
uv pip install pyOFTools