Observations have been made of the growth and collapse of surface and cloud cavitation on a finite aspect ratio hydrofoil oscillating in pitch. The cavitation was recorded using both still and high-speed motion picture photography, and the variations with cavitation number and reduced frequency of oscillation were investigated. The noise generated by the cavity collapse was also measured and an...

A concept of tip vortex cavitation on propellers is described qualitatively, leading to the distinction of trailing vortices, local tip vortices and leading edge vortices. Improvements of the inception behaviour using this distinction are presented. Observations on developed tip vortex cavitation are given to show that the concept of vortex bursting seems inadequate. The problem of "broadband" ...

Calculations of the collapse dynamics of a cloud of cavitation bubbles confirm the speculakions of M#rch and his co-workers and demonstrate that collapse occurs as a result of the inward propagation of a shock wave which grows rapidly in magnitude. Results are presented showing the evolving dynamics of the cloud and the resulting far-field acoustic noise.

Background/introduction Histotripsy ablation of liver tumors is a non-invasive surgery that uses high-intensity acoustic pulses to control an inertial cavitation cloud. Repeated exposure to the cavitation cloud renders a target tissue into a homogenous slurry which is then gradually absorbed by the body. Like other non-invasive surgeries, histotripsy requires a feedback system that can estimate...

Cavitation occurs around dental ultrasonic scalers, which are used clinically for removing dental biofilm and calculus. However it is not known if this contributes to the cleaning process. Characterisation of the cavitation around ultrasonic scalers will assist in assessing its contribution and in developing new clinical devices for removing biofilm with cavitation. The aim is to use high speed...

Amongst the variety of complex phenomena encountered in nonlinear physics, a hysteretic effect can be expected on ultrasound cavitation due to the intrinsic nonlinearity of bubble dynamics. When applying successive ultrasound shots for increasing and decreasing acoustic intensities, a hysteretic behaviour is experimentally observed on inertial cavitation activity, with a loop area sensitive to ...

Collapsing stage of cloud cavity and resulting violent shock pressure have been investigated by many researchers, because the knowledge of cavitation erosion is of practical importance and the dynamics is one of the most challenging problems in the field of two-phase flow. When a researcher intends to investigate the phenomenon numerically or experimentally, he or she must know the structure of...

A passive cavitation detector (PCD) identifies cavitation events by sensing acoustic emissions generated by the collapse of bubbles. In this work, a dual passive cavitation detector (dual PCD), consisting of a pair of orthogonal confocal receivers, is described for use in shock wave lithotripsy. Cavitation events are detected by both receivers and can be localized to within 5 mm by the nature o...