Upward-propagating capillary waves on the surface of short Taylor bubbles

Upward-propagating capillary waves are observed on the surface of short Taylor air bubbles rising in vertical pipes. The wave length distribution along the bubble surface is measured for bubbles rising in pipes of different diameters in stagnant and up-flowing water by digital image processing. It is shown that the waves are generated by bubble bottom oscillations, and their length is determined by wave-current interaction along the liquid film. (C) 2006 American Institute of Physics.