A Study on the Temperature Variation of Rise Velocity for Large Clean Bubbles

Abstract

A series of microphysical laboratory experiments studying the hydrodynamics of single bubbles were conducted to measure the variation of rise velocity, VB, with temperature, T, and radius, r. Bubbles with an equivalent spherical radius between 377 and 4500 ?m were studied for T varying between 0° and 40°C. While for nonoscillating bubbles VB increases with T; due to the significance of oscillations, VB decreases with T for oscillating bubbles, in conjunction with an increase in trajectory oscillations with T. Using observations from this study and data from other researchers, a three-part parameterization of VB(r,?T) is proposed with transitions at Re = 1 and the onset of oscillations, where Re is the Reynolds number. The T for the transition to oscillatory behavior was found to vary linearly with r. An empirical parameterization of VB(r,?T) for oscillatory and nonoscillatory bubbles that correctly incorporates the effect of T is presented.