AN EXPERIMENTAL AND NUMERICAL STUDY ON CAVITATION BUBBLE DYNAMICS AND ITS BIOMEDICAL APPLICATIONS

Abstract

A thorough understanding of cavitation bubble dynamics is critical to mitigate cavitation damage or develop practical applications. An important field of study is the interaction of a single cavitation bubble with neighbouring structure(s). A cavitation bubble collapse near a finite elastic beam, or a rigid wall with an attached hemispherical bubble, are experimentally investigated. A novel low-voltage spark discharge method is also developed, which is capable of generating consistent-sized cavitation bubbles. Numerical simulations using a boundary-element model based on the potential flow theory are conducted to complement these experiments, and also study the interactions between a cavitation bubble and a nearby quiescent air bubble. Lastly, a cavitation bubble interaction with a nearby elastic cell, as well as the mechanisms behind the ultrasound-targeted microbubble disruption of bacterial biofilm are studied. Results identify the interactions between a cavitation bubble and elastic surfaces (beam and sphere), of which the degree of response of these surfaces are found to be dependent to the parameters of the problem such as the dimensionless stand-off distance H'. An air bubble attached to a rigid surface is also found to be capable of negating direct damage due to the cavitation bubble collapse jet. The results also suggest prospective use of cavitation for drug delivery, cell identification, and non-invasive treatment of bacterial biofilm on medical implants by identifying the mechanisms of ultrasound-targeted microbubble disruption of bacterial biofilm.