CFD simulation of cryogenic LH₂ refuelling with boil-off management

Cryogenic liquid hydrogen (LH₂) is emerging as a key enabler for zero-emission transport in aerospace and heavy-duty mobility. Simulating LH₂ refuelling is essential for system design and safety, yet remains challenging due to tightly coupled multiphase phenomena, rapid thermodynamic transients, and limited experimental data. This study presents a high-fidelity 3D CFD methodology for transient LH₂ refuelling under realistic operating conditions. The model combines the Volume of Fluid (VOF) approach with the Lee phase-change formulation and finely resolved real-gas property (RGP) tables derived from NIST data to ensure thermodynamic accuracy near the saturation line. A staged initialization, automatic mesh adaption, adaptive time stepping, and automated boil-off control enable stable and computationally efficient resolution of thermal, flow, and interface dynamics. Inlet boundary conditions are based on measured mass flow rates from an actual LH₂ refuelling campaign, thereby ensuring realistic model input. A dedicated sensitivity study demonstrates that the predicted pressure evolution is strongly affected by the Lee phase-change coefficients, particularly the condensation coefficient, highlighting the need for application-specific calibration. The physical plausibility of the model is supported by comparison with a lumped phase-equilibrium approach, while validation against NASA LH₂ refuelling experiments shows good agreement in the characteristic pressure evolution and liquid fill level. Overall, the developed workflow provides a robust, transferable, and extensible framework for modelling cryogenic LH₂ refuelling and supports future model refinement, parameter calibration, and the optimization and safety assessment of hydrogen storage and refuelling systems in both research and industrial applications.