Mapping the Cavitation Intensity in an Ultrasonic Bath Using The Acoustic Emission

This study presents a new method for identifying and determining the spatial distribution of energy intensity components in an ultrasound bath, focusing on the roles of cavitation activity and the media used, specifically cavitating water and non-cavitating silicon oil. Through measurements and the subtraction of acoustic emission spectra, significant spatial variations in cavitation intensity were observed at various locations within the bath. The local cavitation phenomena were elucidated through the analysis of spectral characteristics, revealing that bubbles at regions of high cavitation intensity exhibit transient motion, while those in low intensity regions demonstrated stable oscillatory motion. Furthermore, the transient collapse of bubbles, which generates local temperature and pressure maxima, was found to correlate with the observed ultrasound effects on chemical systems. The findings underscore that more violent bubble collapses lead to greater cavitation intensity, a conclusion supported by spectral analysis and simulations based on the Gilmore bubble dynamics model.