Localization in an Acoustic Cavitation Cloud

Using a nonlinear sound wave equation for a bubbly liquid in conjunction with an equation for bubble pulsation, we theoretically predict and experimentally demonstrate the appearance of a gap in the frequency spectrum of a sound wave propagating in a cavitation cloud comprising bubbles. For bubbles with an ambient radius of 100 μm, the calculations reveal that this gap corresponds to the phenomenon of sound wave localization. For bubbles with an ambient radius of 120 μm, this spectral gap is related to a forbidden band of the sound wave. In the experiment, we observe the predicted gap in the frequency spectrum in soda water. However, in tap water, no spectral gap is present because the bubbles are much smaller than 100 μm.