Entrance and Cavitation Bubbles

Abstract

The purpose of this memorandum is to present a general discussion of the physical nature of two phenomena : (a) cavitation on underwater projectiles, and (b) the enveloping bubble formed when a projectile enters the water at moderate or high velocities. In this discussion an effort is made to demonstrate a close relationship between the two phenomena. In attempting to explain their various aspects, several hypotheses are advanced concerning the physical mechanisms involved. Although these hypotheses are founded on laboratory measurements and observations, the experimental work is far from complete. Therefore, the explanations and conclusions contained herein are very tentative, and must undoubtedly be revised extensively as the fund of experimental and analytical knowledge increases. However, it was felt that a discussion of these subjects at this time, even though it represents only a transient viewpoint, would be of value if it could serve as a stimulus for discussion and a basis for interchange of experimental information and working hypotheses.