Capillary-hydraulic jump in liquid foams

Description

We study a single, centimeter-long, horizontal, Plateau border (PB). We perturb it locally by dropping a droplet of liquid, which coalesces with the PB, and we follow the dynamics of the subsequent liquid imbibition. Because the PB is horizontal, gravity effects are negligible and the liquid flow is driven by capillarity only. We find that an inertial regime precedes a viscous one, on a critical length that decreases as the bulk viscosity increases. This inertial regime is reported for the first time; it is characterized by the formation of a hydraulic jump, and by a fast (0.1-1 m/s) and constant imbibition velocity. This study should have applications for liquid foam drainage.

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