Benchmarking Hydrogen Dispersion CFD Simulations Using OpenFOAM

Hydrogen and hydrogen-derived fuels are candidate pathways for maritime decarbonisation. However, hydrogen’s wide flammability range and low ignition energy call for a robust assessment of release and accumulation hazards in confined spaces. This paper presents a benchmarking study of hydrogen dispersion in naturally ventilated enclosures using the open-source OpenFOAM solver rhoReactingBuoyantFoam. The solver is validated against published two-vent enclosure experiments covering two enclosure volumes, two nozzle diameters, and releases ranging from buoyancy-dominated plumes to high-momentum jets. Sensitivity studies were performed on the mesh, the turbulence model, the buoyancy term in the turbulence model, and the turbulent Schmidt number. The standard k − ε and k-ω SST models predict similar ceiling hydrogen concentrations, but the k-ε model gives a thicker stratified layer. Adding a buoyancy production term in the turbulence model has a negligible effect. Across all conditions, the predicted ceiling hydrogen concentration agrees well with the measurements, and the simulated vertical profiles reproduce the stratified ceiling layer, although the simulated layer is thinner than measured. The flow regime at the ceiling, characterised by the Morton number, explains the effect of nozzle diameter and the prediction errors in the 1 m3 enclosure. In the 2 m3 enclosure, the systematic under-prediction, most noticeable at low flow rates, points to additional factors. These results provide a validated basis for applying OpenFOAM to hydrogen release scenarios, and the full simulation setup is publicly available.