Withdrawal from Two‐Layer Fluid Through Line Sink

Abstract

A series of experiments is described in which water is withdrawn through a narrow slot in the bottom corner of a flume containing two layers of water of different density. A range of interface thicknesses, density differences, and flow rates is considered. Results are presented, which provide an estimate for the critical drawdown value of the Froude number, above which the interface is drawn down into the sink and the upper layer begins to flow out through the slot. This critical value was found to depend upon the value of interface thickness, and an empirical form for this dependence is presented. These results are discussed in the light of recent numerical computations of the shape of a very thin interface between the two layers at various values of the Froude number, and compared with previous results on this and the related three-dimensional problem of withdrawal through a single point. Suggestions are made for further research required to fully resolve this problem.