Distortion of Fluid Drops in the Stokesian Region

IN an investigation of circulation inside drops moving in a viscous medium, the drop size has been varied in order to determine the factors affecting the minimum size at which circulation can be detected. With some systems, such as water drops in castor oil, circulation commences at a Reynolds number in the range 0.03–0.1 (drop diameter 10–20 mm.), whereas with other systems such as chloroform or carbon tetrachloride in glycerol, circulation begins at much lower Reynolds number of 0.0003–0.001 (drop diameter 1–3 mm.). The interfacial tensions of the two systems are not widely different.