The Phase Diagram of Leaking Flows

When a pipe springs a leak, the exiting fluid can either jet away cleanly, dribble down along the surface, or not flow out at all. Past investigations of this “teapot effect” have focused on jetting and dribbling liquid flows separately as functions of initial flow velocity, wetting, and viscosity, but there has been little focus on the transition between flow regimes. In this work, we characterize a liquid leaking from a small hole as the flow transitions from jetting to dribbling, and dribbling to no flow. We map the phase diagram of these leaking flow transitions as a function of hydrostatic pressure and pipe tipping angle, and investigate the contributions of fluid viscosity, hole size, and surface wetting to the boundaries on this phase diagram.