CryoFoam: A practical numerical framework for non-isothermal two-phase flows in cryogenic fluids with phase change.

An accurate prediction of non-isothermal gas–liquid interfaces in cryogenic two-phase flows is crucial for the high-efficiency energy storage, transportation, and utilization of liquid hydrogen. However, temperature difference and interfacial mass and energy transport can change the thermodynamic state of gas–liquid interfaces and thereby impact the distribution. And the lower surface tension coefficient and viscosity of liquid hydrogen, compared to room-temperature fluids, increase the likelihood of the instability and breakage of non-isothermal interfaces. Conventional numerical methods suffer from a scarcity of precision and the propagation of spurious velocities in predicting such flows. In this study, a new numerical framework called cryoFoam was developed based on an open source CFD code OpenFOAM to address the issue of the inaccurate capture of non-isothermal cryogenic interfaces. A practical interface-capturing model involving phase change was implemented to achieve the uniform distribution of surface forces in both gas and liquid phases. The tangential surface force was incorporated into the governing equations to realize thermocapillary convection. The Schrage model, a widely-used phase change model, was employed to deal with condensation and evaporation. The performance of the solver was assessed using five benchmarks which involve thermocapillary flows and phase changes in liquid hydrogen, liquid oxygen, liquid nitrogen, and liquid methane. The results show that the new method can reduce large spurious velocities and prevent the distortion of isotherms near the curved interface in cryogenic fluids. It demonstrates higher precision than the traditional VOF method in predicting cryogenic thermocapillary convection and interfacial energy transport. • A new CFD code was developed to model the non-isothermal two-phase flows in liquid hydrogen. • A practical interface-capturing model involving phase change was implemented. • The tangential surface force was employed to realize thermocapillary convection. • Spurious velocities and the distortion of isotherms in liquid hydrogen were reduced. • The method presents high accuracy in predicting mass and energy transport at cryogenic interfaces. [ABSTRACT FROM AUTHOR]