Oscillation frequencies of freely suspended water drops

Abstract

An investigation of water-drop oscillations was undertaken through the analysis of high-speed films of water drops suspended in a large vertical wind tunnel. Measurements of the natural frequency of vibration of suspended water drops versus diameter were made for drops ranging in size from 1 to 7 mm. A theoretical formula derived by Lord Rayleigh in 1879 predicts that, for small spheroidal oscillations of a water drop, the frequency is proportional to the diameter raised to the −3/2 power. Although our drops were suspended at their terminal velocity and were significantly deformed, the data agree with both the power dependence and the coefficient of proportionality.