The Micro-flow Distribution And Interaction Between Cavitation Bubbles And Suspended Particles Under The Action Of Ultrasound

Acoustic cavitation is the formation in liquid irradiated with a powerful ultrasonic wave.The applied range of ultrasonic wave is wide,such as microbubble contrast technique,ultrasonic cleaning,ultrasound extraction and high intensity ultrasound therapy.The multiple bubbles dynamics is fundamental to study on the cavitation effect.The application of ultrasound in liquid has a broad range,but the transmission medium irradiated with the application of ultrasonic wave usually is complex medium,for example a mixture of liquids and particulate impurities(or particles,membrance coating,etc),as well as a mixture of different kinds of liquids,besides,there may be bubbles in the liquid.So it is important to study the interaction between bubbles and suspended particles for the application of medicine and cavitation damage.There is a lot of research about single bubble dynamics by many scholars,but as far as the theoretical research about the interaction between bubbles and particles is still relatively backward,most of which are experimental research.Similarly,microstreaming around suspended sphere and oscillating bubbles is still being explored.Based on this,the interaction between bubbles and suspended particles and microstreaming around suspended sphere and bubbles in liquid for plane wave are analyzed and studied.The main emphasis of our research is the theoretical derivation and numerical simulation of the interaction and microstreaming velocity generated by a rigid sphere and a bubble for plane wave.The main contents include the following aspects:1.The expression of the scattering field of rigid sphere and non-rigid sphere for plane wave in liquid are derived and given based on the acoustic wave theory,which laid the foundation of the further study of microstreaming around suspended sphere and bubbles.2.The expression of the microstreaming velocity around a suspended sphere and a bubble in an unbounded viscous liquid is derived based on the theory of acoustic scattering.The effects of bubble radius,the separation distance between a bubble and a rigid sphere and the relative position of medium are analyzed.It has been demonstrated that the velocity around the bubble and rigid sphere is related to the relative position of medium.The increment of neighboring bubble radius makes acoustic streaming stronger,while the increment of distance between a bubble and a rigidity sphere induce the acoustic streaming weaker.3.The expression of three coupling dynamic equation of a particle and an oscillating bubble in liquid for plane wave is derived and given.The derivation of the model is based on the multipole expansion of the particle and bubble velocity potentials and the use of Lagrangian mechanics.The effects of the density of the particle,the size of bubble and particle,the driving frequency and acoustic pressure amplitude on interaction between bubble and particle are investigated.It has been demonstrated that the time-averaged interaction between the light particle(?s/?l=0.5)and bubble repel,but the time-averaged:interaction between bubble and the neutral(?s/?l=1)or heavy(?s/?l=1.5)particle attract.The size of bubble and particle as well as the driving frequency and acoustic pressure amplitude can also affect the interaction between the particle and bubble.