RfbFoam

RfbFoam is an open-source computational fluid dynamics (CFD) solver for simulating redox flow battery (RFB) systems in OpenFOAM. It couples momentum, mass, and charge transport phenomena to model electrochemical processes in porous electrode structures with Butler-Valmer kinetics and mass transfer effects.

Redox flow batteries are rechargeable electrochemical devices that store electrical energy in reversible redox couples dissolved in flowing electrolyte solutions. They are a promising technology for grid-scale stationary energy storage, offering the key advantage of decoupling power density (stack size) from energy capacity (electrolyte volume). RfbFoam provides a continuum-scale simulation tool to study the coupled hydrodynamic and electrochemical performance of RFB half-cells, enabling design optimization and performance prediction.

Key Features

• Coupled multiphysics: Simultaneous solving of momentum, mass, and charge transport with electrochemical reactions
• Symmetric cell modeling: Half-cell setup for redox flow battery analysis
• Porous media treatment: Support for both Bruggeman correlation and explicit tortuosity effects
• Advanced boundary conditions: Custom fixedCurrent boundary condition for current density control
• Parametric studies: Automated batch processing via Python scripts for generating polarization curves
• Geometric flexibility: Complex flow field geometries including FTFF and IDFF designs via STL-based meshing
• Validation cases: Comparison with COMSOL Multiphysics and experimental data

What Does RfbFoam Solve?

RfbFoam addresses the multiphysics nature of redox flow batteries by simultaneously solving:

Physics	Description
Momentum transport	Fluid flow through porous media (Navier-Stokes with Darcy-Forchheimer terms)
Mass transport	Species diffusion and convection for oxidized (O) and reduced (R) species
Charge transport	Electrical potential in both solid (electrode) and liquid (electrolyte) phases
Electrochemical reactions	Butler-Volmer kinetics with mass transfer limitations

Repository Structure

RfbFoam/
├── src/                     # Solver source code
│   ├── RfbFoam.C           # Main solver application
│   ├── BCs/                # Custom boundary conditions
│   ├── equations/          # Transport equation definitions
│   └── Make/               # Compilation settings
├── examples/               # Example cases and tutorials
│   ├── cases/              # Ready-to-run simulation cases
│   └── verification-validation/  # Validation against experimental data
├── batch_run/              # Python tools for parametric studies
└── doc/                    # This documentation

Applications

• Battery design optimization: Flow field geometry and electrode structure evaluation
• Performance prediction: Current-voltage characteristics and efficiency analysis
• Scale-up studies: From lab-scale to industrial systems
• Parametric analysis: Operating conditions and material properties sweeps
• Validation studies: Model verification against experimental data

License

RfbFoam is licensed under the GNU General Public License v3.0.

Acknowledgements

This research has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 101150565 (TopeSmash project). Moreover, this work is supported by the ERC grant FAIR-RFB (ERC-2021-STG 101042844).

note

Detailed modeling of membrane processes (determining ohmic losses and crossover) is not included in the current version.