Transport of coarse particles in liquid foams: coupling of confinement and buoyancy effects

Abstract

We investigate the behavior of coarse particles confined in foam channels during drainage. Results are reported for particle velocities measured at both microscopic (single foam channel) and macroscopic (foam) scales, as a function of the average velocity of the liquid flow and of the confinement parameter that is the ratio of particle diameter to the maximal particle diameter within channel cross-section. Thanks to numerical simulations, we show that velocities measured for small values of the confinement parameter cannot be understood with the commonly assumed theory for liquid flow in foam channels. Instead, better agreement is obtained by taking into account the characteristics of the flow in the films/channel transitional areas. Finally, values for longitudinal dispersion coefficients are reported, emphasizing effects of buoyancy on particles motions.