Cavitation bubbles with a tunable-surface-tension thermal lattice Boltzmann model

Abstract

The effects of surface tension and initial input energy on cavitation properties based on a tunable-surface-tension large-density-ratio thermal lattice Boltzmann method pseudo-potential model are investigated. The validity and superiority of the proposed model in simulating the D2 law, Laplace law, and revised thermal two-dimensional Rayleigh–Plesset equation are demonstrated. Moreover, the lattice Boltzmann method was used to study the effects of varied surface tension on cavitation bubble properties for the first time, and the maximum surface tension-to-minimum surface tension ratio of 25 is utilized, which is highly improved compared with previous numerical simulations (<4) and makes our result more clear. The simulation results indicate that for an infinite liquid, the increase in the surface tension will improve the collapse intensity of cavitation bubbles, increasing the collapse pressure, velocity, and temperature and meanwhile reducing the bubble lifetime. For the cavitation bubbles collapsing near a neutral wall, with an increase in the surface tension, the collapse pressure, temperature, and cavitation bubble lifetime trends are the same as in the infinite liquid. However, the collapse velocity is affected by the neutral wall, and the micro-jet becomes wider and shorter. The maximum cavitation bubble radius in an infinite liquid is nearly linearly proportional to the input initial energy. An increase in the surface energy reduces the maximum radius of the cavitation bubbles, while increasing the pressure energy and thermal energy promotes the maximum radius of the cavitation bubbles. This series of simulations proves the feasibility of the proposed model to investigate the thermodynamic process of the cavitation bubbles with high density ratios, wide viscosity ratios, and various surface tensions.