LAUSR

Microbubbles (MBs) usually exist in polydisperse populations and often strongly interact with each other. Accurate investigation of the dynamics of the MBs requires considering the interaction between Microbubbles. We have developed an efficient method for numerically simulating N interacting MBs. The subharmonic (SH) responses of a polydispersions of 3-52 microbubbles with sizes between 2-5 microns, excited with ultrasound with a frequency and pressure of 1.8-8 MHz and 1-500 kPa were investigated. We show that if the frequency is set to the SH resonance of the larger MBs, the smaller MBs oscillations are controlled by the larger MB and the SH amplitude of the population of MBs increases. For small enough distances between MBs, one large MB may control the oscillations of the rest. If the excitation frequency is equal to the SH resonance of the smaller MBs, there exists two pressure regions. For lower pressures, the oscillations of the larger MB are out of phase with the smaller MBs and the resulting SH a...