Internal hydraulic jumps at T-junctions

This paper presents a theoretical investigation of the occurrence of hydraulic jumps in two-layer systems induced by extraction of fluid from the upper layer. The physical configuration consists of a horizontal main pipe along which air and water flow, and a vertically upward side arm. An hydraulic model based on the momentum principle assuming that the fluids do not mix is developed that leads to at least two possible conjugate states for any given two-layer flow. A method of determining the amount of gas which must be extracted into the side arm for a jump to occur is developed and predictions shown to be in reasonable agreement with observation. Unusually, it is shown that above this critical gas take-off value two possible states remain energetically feasible.