A Study Of The Dynamic Behavior Of Bubbles In A Spherical Liquid Cavity

High-intensity ultrasonic waves acting on liquids will cause complex cavitation phenomena,resulting in extreme effects such as local high temperature?high pressure and shock waves,which can promote chemical reactions and material exchange to a certain extent.In recent years,many scholars have conducted extensive and in-depth research on the cavitation phenomenon of bubbles under the action of ultrasound.Predecessors have developed relatively mature single bubble dynamics models in unbounded liquids.Ultrasound shows broad application prospects,such as ultrasonic cleaning,ultrasonic extraction,tumor ablation,etc.However,the actual effect of ultrasound is a complex system.The liquid contains cavitation bubbles,different kinds of particles,etc.,and the liquid is wrapped by the medium.The interaction of bubble,particle and the medium outside the cavity will affect its own motion and cavitation effects.Based on this,this paper studies the interaction between bubble and particle in the cavity and the vibration behavior of the bubble itself,focusing on the influence of the cavity structure and medium characteristics on the bubble and the interaction between the bubble and the particle.To lay a foundation for understanding the dynamics of cavitation bubbles in a complex environment,it mainly includes the following aspects:1.Starting from the velocity potential of bubble,particle and sphere,combining the kinetic energy and potential energy of the system and based on Lagrangian equations,the dynamic equations of bubble and particle are derived.The effects of sound field parameters,media elasticity,density,and bubble particle properties on the bubble resonance frequency and bubble particle motion are studied respectively.The results show that the particle has tendency to move toward the cavity wall,and the translational characteristics of bubble is related to the interaction between bubble and particle.2.The mechanical properties of the viscoelastic medium outside the cavity is characterized by using the Voigt viscoelastic model.On this basis,the bubble dynamics model in the muscle tissue is obtained.The effects of bubble and cavity radius ratio,viscoelasticity of the medium outside the cavity,and acoustic field parameters on the bubble resonance frequency,radial vibration and bubble inertial cavitation threshold are studied respectively.Numerical analysis shows that the smaller the cavity radius,the stronger the suppression of bubble vibration,and the bubble vibration amplitude is small at high frequency.In the range of size less than l?m,the smaller the bubble,the higher the threshold,the more difficult it is to cavitation.3.Consider the density of the medium outside the cavity and make further corrections to the bubble dynamics in the soft tissue.Based on the bubble dynamic equation and bubble linear resonance equation,the resonance frequency of the bubble,the stress in the tissue and the bubble threshold are analyzed.The results show that the density of the medium outside the cavity has a certain effect on the resonance frequency of the bubble,and it is more obvious when the cavity is small.In the low-frequency and high-shear modulus tissue,the tissue stress presents more obvious fluctuation characteristics,and the inertial cavitation threshold of the bubble also appears as a more complex feature.