The ultrasonic cavitation exhibits complex physical behavior in aluminum melt

and collapsing acoustic cavitation bubbles can result in instantaneous high pressure shock wave and jet flow in the partial zone of aluminum melt

which can play a key role in refining the grain size as a result of broken dendrite in the alloy.Based on the finite element method

effects of high pressure shock wave formed in the process of bubble collapse on aluminum melt change were simulated.Numerical simulation reveals that the instantaneous maximum pressure and maximum jet flow velocity can reach 105MPa and 400 m/s

respectively.Mechanism of cavitation effects refining grain size in aluminum alloy are described theoretically.Mathematical model for cavitation effects on melt super-cooling and dendrite broken is established.In addition

problems in simulation are presented.