Three-Dimensional Density Current

A laboratory investigation of a three-dimensional density current is described. The density current was produced by the release of salt water at the upper end of a sloping floor immersed in a tank of fresh water. The flow regime was classified as laminar, indeterminate, or turbulent for floor slopes up to 20○ to the horizontal. The lateral spread of turbulent flows was correlated with a Richardson number measured at the injection orifice. Detailed measurements of velocity and density were made at three cross sections of one turbulent density current on a floor of slope 20○. The velocity and density distribution were found to be reasonably self preserving when described in terms of two characteristic length scales, one a characteristic width and the other a characteristic height of a cross section. The maximum velocity varied as X^-0.7 where X was the distance from a finite virtual line source used' to locate the free boundaries of the flow. The mean density excess varied as X^-1.1. The entrainment constant E was found to decrease in the direction of flow.