Selective withdrawal from an intake channel connected to a reservoir

This paper investigates selective withdrawal from an intake channel connected to a two-layer stratified reservoir using a line sink located at the downstream end of the intake channel. Such a withdrawal scenario is commonly observed at intake channels, skimming operations, and pump intake bays. This study formulates mathematical expressions for such a withdrawal scenario in order to extend our knowledge and to develop a mathematically simpler method in the case where a solution already exists. An expression to compute the incipient Froude number was developed considering the effect of a boundary. Expressions were developed to obtain discharge ratios for the scenarios when the line sink is located at the channel bottom and far away from the channel bottom. When the interface is located below the channel bottom and only at the reservoir, the intake channel itself behaves as a rectangular orifice, and an expression to compute the incipient Froude number for such a case was developed. The mathematical results were compared to the results obtained from a computational fluid dynamics solver and other relevant published studies.