FROTH INSTABILITY IN SMALL-OVER-LARGE BUBBLE LATTICES

For different bubble diameters arranged in a nearly two-dimensional froth or lattice, a fluid instability is predicted. The first-order stability analysis yields conditions for growth of the most unstable wavenumber both as a function of bubble diameter and dimensionless Bond number. Gravity acts to distribute the greater fluid mass associated with smaller bubbles, while surface tension stabilizes the entire lattice against perturbations. The phenomenon evolves somewhat akin to a Rayleigh-Taylor mechanism and in addition to its fundamental interest, carries implications for predicting solute redistribution and gravitational alignments in bubble columns.