S02 超音波キャビテーションからの広帯域雑音 : 気泡数変動と気泡間相互作用(特別講演2)

抄録

Numerical simulations of acoustic cavitation noise have been performed under the experimental condition of Ashokkumar et al. [J. Am. Chem. Soc. 129, 2250 (2007)]. It is shown that the broadband noise is mainly originated in the temporal fluctuation in the number of bubbles. In other words, the broadband noise is originated in transient cavitation if transient cavitation is defined as the cavitation of bubbles with short lifetime due to fragmentation. The broadband noise is also resulted from non-periodic (chaotic) pulsation of bubbles. When the number density of bubbles is very large, the broadband noise is intensified by the bubble-bubble interaction. The bubble-bubble interaction is the influence of acoustic waves radiated from neighboring bubbles on the pulsation of a bubble.