Transient bubbles interacting with an attached cavity and the boundary layer

Experiments on two-dimensional cavitating hydrofoils show important differences in global behaviour of flows according to the population of air nuclei conveyed by the liquid. By means of visualization techniques and flow modelling, the major features of attached-cavity flows and transient-bubble flows are revealed. The main topics of the paper are: cavitation inception in either regime, hydrofoil saturation and the sweeping away of a cavity by bubbles. The main conditions for the validity of the λ−3 similitude rule are delineated. Special attention is given to the mechanism of interaction between the exploding bubbles, the attached cavity and the boundary layer. Estimates of the critical number of active nuclei for saturation and cavity suppression which agree with experimental results are given.