This paper concerns the translational forces exerted on pulsating air bubbles in a stationary sound field. These forces, normally called Bjerknes forces, are derived by simple arguments and classified as to their origin. Measurements have been made of the relative velocity of appoach of two bubbles undergoing a mutual Bjerknes force. The measurements were made in a rigid glass container oscillated in a vertical direction at 60 Hz by a shaker table. The ambient pressure above the liquid was reduced in order to obtain large pulsations, and the attracting bubbles were photographed with a movie camera. Oberved and calculated values for the velocity of approach are in agreement provided a drag law assuming interfacial slippage is used.
Subject Classification: 25.60.