Inertial Mass Transport and Capillary Hydraulic Jump in a Liquid Foam Microchannel

We report a capillary-inertial flow in an unbounded liquid microchannel-a Plateau border in a liquid foam-and discuss its relevance for foam drainage. In contrast to the case of jets of cylindrical geometry, which are susceptible to the Rayleigh-Plateau instability, in this channel, any liquid perturbation is dispersed instead of amplified. The geometry of the Plateau border provides an effective negative surface tension that triggers the liquid redistribution. The dynamics is perturbation independent and leads to the formation of a hydraulic jump, at the micron-millimeter scale, traveling at constant velocity.