Cavitation Streamers and Surface Wave Phenomena

Abstract

Consecutive frames of motion pictures (4 sound cycles/frame) of cavitation streamers on the face of a vibrating probe (20 kc/sec) frequently show the continuous growth of bubbles to an apparently critical size, followed by a rapid shrinking or sudden disappearance. A faint cloud is often seen in the place of the large bubble, as if the latter had suddenly subdivided into a large number of bubbles of microscopic size. One is reminded of Willards' demonstration that a cloud of microbubbles is formed when a resonant bubble executes vigorous surface oscillations. Detailed information on events similar to the Willard phenomena has been obtained by study of a low-frequency device. A rectangular tube with transparent walls is mounted with axis vertical, partially filled with liquid, and tightly capped. It is set into vertical oscillation at 50- to 150-cps frequency and 0- to 3-mm peak-to-peak amplitude. Motion pictures will be shown, in which one sees the onset of surface waves, the development of crests into long liquid filaments which pinch off into droplets, and the encapsulation of air by arching over of the crests. Relevant theory has been given by Benjamin and Ursell and by G. I. Taylor. (Supported in part by the U. S. Public Health Service.)