Experimental studies on the shape and path of small air bubbles rising in clean water
This Letter reports experiments on the shape and path of air bubbles (diameter range 0.1–0.2 cm) rising in clean water. We find that bubbles in this diameter range have two steady shapes, a sphere and an ellipsoid, depending on the size of the capillary tube from which they detach. The spherical bubbles move significantly slower than the ellipsoidal ones of equivalent volume. Bubbles with diameter less than about 0.15 cm rise rectilinearly. The larger spherical bubbles follow zigzag paths while the larger ellipsoidal bubbles follow spiral paths.
© 2002 American Institute of Physics. Received 21 August 2001; accepted 24 April 2002; published 23 May 2002. We gratefully thank Professor P. G. Saffman, B. Homsy, A. Prosperetti, and J. Magnaudet for insightful discussions on the subject. We acknowledge undergraduate students Erin Englert and Marin Markov from Occidental College and Ben Welander from Caltech for their help during experimental work. This work is supported by the National Science Foundation (CTS-0121340), the Research Corporation (CC4612), and the Office of Naval Research (N00014-98-1-0017).
Published - PhysFluids_14_L49.pdf