Secondary Acoustic Waves in a Polydisperse Bubbly Medium.

Wave interaction of bubbles in a cavitation cluster is studied theoretically and experimentally. It is found that two groups of bubbles with different phases of oscillations and collapse time are formed at the early stage of bubble‐cluster formation. It is shown that small bubbles accumulating energy in the initial pulsed acoustic wave collapse in the field of internal positive pressure of the cluster. A secondary compression wave generated by inertial expansion of large bubbles is determined by means of numerical simulation and registered experimentally. The amplitude of this wave is comparable to the amplitude of the initial pulse. A decrease in the oscillation period and strengthening of the microbubble collapse are observed in the cluster under pulsed compression. [ABSTRACT FROM AUTHOR]