On the deformation of gas bubbles in liquids

We consider the deformation of gas bubbles rising in different liquids over a wide range of Morton numbers, from O(10(-11)) to O(1), and bubble diameters. We have collected data from the literature and performed new experiments for relatively large Morton numbers. A simple expression is proposed to describe the evolution of the bubble deformation, which is consistent with the analytical solution of Moore [The rise of a gas bubble in a viscous liquid, J. Fluid Mech. 6, 113 (1959)]. It appears that deformation can be predicted correctly by considering the Morton and Weber numbers. The variation of the bubble interfacial area is also analyzed; this quantity is very important for the case of bubbly flow modeling but has not been measured directly to date. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4705527]