Bubble kinetics in a steady-state column of aqueous foamK. Feitosa, O. L. Halt, R. D. Kamien and D. J. Durian
Department of Physics and Astronomy, University of Pennsylvania 209 S. 33rd Street, Philadelphia, PA 19104-6396, USA
received 21 July 2006; accepted in final form 18 September 2006
published online 13 October 2006
We measure the liquid content, the bubble speeds, and the distribution of bubble sizes, in a vertical column of aqueous foam maintained in steady state by continuous bubbling of gas into a surfactant solution. Nearly round bubbles accumulate at the solution/foam interface, and subsequently rise with constant speed. Upon moving up the column, they become larger due to gas diffusion and more polyhedral due to drainage. The size distribution is monodisperse near the bottom and polydisperse near the top, but there is an unexpected range of intermediate heights where it is bidisperse with small bubbles decorating the junctions between larger bubbles. We explain the evolution in both bidisperse and polydisperse regimes, using Laplace pressure differences and taking the liquid fraction profile as a given.
83.80.Iz - Emulsions and foams.
82.70.Rr - Aerosols and foams.
© EDP Sciences 2006