The enhanced effect of collapse strength of a dual-frequency driven bubble in 2-dimensional space

Abstract

The bubble-collapse strength is closely related to the ultrasonic cavitation effect. The enhanced effect of collapse strength of a dual-frequency driven bubble is one of the mechanismsunderlying the synergistic effect of dual-frequency excitation. In this paper, the growth rate of bubble-collapse strength is defined as:G=(Rmax,d′-Rmax,s′)/Rmax,s′, where Rmax,s′and Rmax,d′are the bubble maximum oscillation radius under single- and dual-frequency exciting, respectively. The enhanced region I (below the main resonances line), II (above the main resonances line) and III (around the diagonal line) concerning to the bubble-collapse strength in f1-f2 plane are analyzed. The results show that the enhanced effect of bubble-collapse strength is implicated in the acoustic pressure, bubble equilibriumradius and pressure amplitude ratio. This paper could be helpful for optimizing the dual-frequency operation from the perspective of bubble radial dynamics.