Abstract: The process of near-wall cavitation bubble collapse was simulated by using Lattice Boltzmann pseudo-potential cavitation model with tunable surface tension and large density and viscosity coefficient ratio.Furthermore,the influence of surface tension and the initial pressure difference between inside and outside the bubble on the flow field distribution was analyzed,and the relationship between surface tension and maximum micro-jet and collapse pressure was investigated.The results indicate that,with the decrease of surface tension,the range of high-pressure region above the cavitation bubble increases,while the range of low-pressure region between bubble and wall decreases in the final collapse stage.The smaller surface tension intensifies the deformation of the gas-liquid interface,resulting in a more concentrated micro-jet.In addition,more surface energy accumulated during cavitation bubble collapse strengthens the collapse intensity,leading to the increase of the maximum micro-jet velocity and collapse pressure.However,with the increase of pressure difference between inside and outside the cavitation bubble,the effect of surface tension is reduced.Besides,the smaller surface tension leads to the shorter lifetime of cavitation bubble,which increases the Bjerknes force and aggravates the trend of cavitation bubbles collapse towards the wall.

Key words: cavitation bubble collapse, surface tension, collapse pressure, lattice Boltzmann method, micro-jet