Numerical study on collapsing cavitation bubble dynamics in cryogenic fluids

The paper addresses the implementation of a dual distribution function multiphase lattice Boltzmann method (DDF-MLBM) for studying the collapse of cavitation bubbles in cryogenic liquids. The present scheme incorporates the energy equation and imposes interparticle interactions and fluid–solid adhesive forces through the exact difference method (EDM). To accurately model phase changes and the molecular complexities of cryogenic fluids like liquid hydrogen ($L{H}_2$) and liquid nitrogen ($L{N}_2$), the Peng-Robinson (PR) equation of state is employed along with an acentric factor. The accuracy of the present numerical technique is evaluated using the Laplace law and the Maxwell equal area construction theorem for a two-phase liquid–vapor system in equilibrium. For transient solutions, the study compares results of heterogeneous cavitation with the analytical solution derived from the thermal Rayleigh-Plesset equation. The research investigates the impact of the distance between a cavitation bubble with an adjacent solid wall on velocity, pressure, temperature, and collapse time. Furthermore, it is assessed how surface wettability influences cavitation bubble collapse intensity. Additionally, the paper examines the collapse of a cavitation bubble cluster and evaluates the effects of different physical parameters on the collapse properties of the bubble cluster. The results underscore the significant influence of the distance between cavitation bubbles in the cluster, the distance between bubbles and the adjacent solid surface on the micro-jet velocity. Moreover, it is found that increasing the contact angle of the solid surface enhances the collapse intensity and micro-jet velocity of the collapsing bubble cluster.