foam2exodus

A converter utility that translates OpenFOAM mesh and field data into the Exodus II database format.

Overview

foam2exodus is a tool designed to convert OpenFOAM computational fluid dynamics (CFD) cases into the Exodus II format, a widely-used database format for finite element analysis. The Exodus II format enables visualization and post-processing in various scientific visualization tools such as ParaView, VisIt, and others.

Current Status (Under Development)

Currently Implemented:

• Serial OpenFOAM mesh conversion (ASCII and binary formats)
• Conversion of mesh geometry (points, cells, faces)
• Boundary patch export as Exodus sidesets
• Support for hexahedral, tetrahedral, and pyramid cell types
• Cell zones preservation

Planned Features:

• Field data conversion from all time directories
• Parallel OpenFOAM case support
• Option to generate single or decomposed Exodus database files according to user preference
• Time-series data export

Prerequisites

Required Software

1. CMake (version 3.10 or higher)

   cmake --version  # Check your version

2. C++ Compiler with C++17 support

   • GCC 7.0+ or
   • Clang 5.0+ or
   • Any C++17 compliant compiler

3. NetCDF Library (with C interface)

   • Development headers and libraries are required

   Installation on Ubuntu/Debian:

   sudo apt-get install libnetcdf-dev pkg-config

   Installation on Fedora/RHEL/CentOS:

   sudo yum install netcdf-devel pkgconfig

   Installation on macOS (using Homebrew):

   brew install netcdf pkg-config

4. pkg-config

   • Used by CMake to locate NetCDF installation
   • Usually comes pre-installed on Linux systems
   • On macOS: brew install pkg-config

Building from Source

Step 1: Clone or Navigate to the Repository

cd /path/to/foam2exodus

Step 2: Create Build Directory

mkdir build
cd build

Step 3: Configure with CMake

cmake ..

If NetCDF is installed in a non-standard location, you may need to help CMake find it:

export PKG_CONFIG_PATH=/path/to/netcdf/lib/pkgconfig:$PKG_CONFIG_PATH
cmake ..

Step 4: Compile

make

For faster compilation on multi-core systems:

make -j$(nproc)  # Linux
make -j$(sysctl -n hw.ncpu)  # macOS

Step 5: Install (Optional)

sudo make install

This will install the foam2exodus executable to /usr/local/bin by default.

Usage

Basic Syntax

foam2exodus <OpenFOAM_case_dir> <output.exo>

Advanced

Convert multiple meshes and merge into single exodus file

foam2exodus --multiple <OpenFOAM_case_dir_1> <OpenFOAM_case_dir_2> <output.exo>

Arguments

• <OpenFOAM_case_dir>: Path to the OpenFOAM case directory containing the constant/polyMesh folder
• <output.exo>: Desired path and filename for the output Exodus II database file

Examples

Convert a serial OpenFOAM case:

./foam2exodus /path/to/openfoam/case myMesh.exo

Convert and specify full output path:

./foam2exodus ~/simulations/cavity ~/results/cavity_mesh.exo

Output

The converter will display:

• Mesh statistics (number of points, cells, boundary patches)
• Progress information
• Success/error messages

Boundary patches from OpenFOAM are automatically exported as sidesets in the Exodus file, preserving their names and topology.

OpenFOAM Mesh Format Support

Supported Formats

• ASCII format (human-readable text files)
• Binary format (OpenFOAM binary mesh files)

Supported Cell Types

• Hexahedra (hex)
• Tetrahedra (tet)
• Pyramids (pyramid)

Mesh Components

• Points (vertices)
• Faces
• Cell connectivity
• Boundary patches
• Cell zones
• Owner/neighbour cell relationships

Project Structure

foam2exodus/
├── CMakeLists.txt           # CMake build configuration
├── README.md                # This file
├── foam2exodus/
│   ├── main.cpp            # Main entry point
│   ├── src/
│   │   ├── OpenFOAMMeshReader.h    # OpenFOAM mesh reader interface
│   │   ├── OpenFOAMMeshReader.cpp  # OpenFOAM mesh parser implementation
│   │   ├── ExodusWriter.h          # Exodus II writer interface
│   │   └── ExodusWriter.cpp        # Exodus II database writer
│   └── examples/           # Example test cases
└── build/                  # Build directory (created by user)

Troubleshooting

CMake Cannot Find NetCDF

If you encounter:

Could not find module FindNetCDF.cmake

Ensure:

1. NetCDF development packages are installed
2. pkg-config is installed and functional
3. PKG_CONFIG_PATH includes the NetCDF pkgconfig directory

Test NetCDF installation:

pkg-config --modversion netcdf

Compilation Errors

If you see C++17-related errors, ensure your compiler supports C++17:

g++ --version  # Should be 7.0 or higher
clang++ --version  # Should be 5.0 or higher

Runtime Errors

"Cannot find polyMesh directory"

• Ensure the OpenFOAM case directory contains constant/polyMesh/
• Verify the case path is correct

"Error reading mesh files"

• Check that mesh files (points, faces, owner, neighbour, boundary) exist
• Verify file permissions are readable

Contributing

This project is under active development. Contributions, bug reports, and feature requests are welcome.

Licence

BSD-3-Clause. See file headers for details.

Copyright (c) 2026 CCFNUM, Lucerne University of Applied Sciences and Arts.

Contact

• Project Maintainer: Lucian Hanimann (lucian.hanimann@hslu.ch)