Experimental Study of Concentration Profile in Interflow Density Current

Gravity currents, also called density currents or buoyancy currents, are flows driven by the density difference between the flow and its ambient environments. When a gravity current reaches the level of neutral buoyancy in a stratified water body, it can separate from the bed as an intrusion. Laboratory experiments are performed to investigate dense flow behavior in stratified ambient in this study. Experiments were carried out on 2.5% bed slope by 4 discharges, 1, 1.5, 2 and 2.5 l/s, and 4 concentrations 5, 10, 15 and 20 mg/l, that created current with a density of 1003.2, 1006.3, 1009.4 and 1012.5 respectively. Stratification was made by mixture of water and salt with vertical gradient. For creating density flow, silica particles with 8 diameters in average and density of 2.673 g/cm3 was used. To investigate the concentration profile, density and concentration were measured in three sections along the flume with three centimeters interval in depth using siphon mechanism. Experimental observations showed that the currents would separate from the bed and then horizontally intrude into the ambience and the density of ambient fluids below the separation point decreases. The measurements in this study indicate that the maximum concentration depth and thickness of body current decreases with increasing concentration in interflow and body current thickness stabilize with increasing discharge.