عنوان مقاله [English]
One of the most important problems arising after the construction of a dam is sedimentation in the dam’s reservoir. In turn, one of the phenomenon that may affect the sedimentation is density currents. A density current is, indeed, the movement of a fluid through another one that has a different density. If there was saline stratification in the vertically downward direction in the reservoir of the static fluid, density current occurs as interflow. Kao (1977) derived the flow diffusion velocity along a common surface between two homogeneous fluids based on Bernoulli's theory. Likewsie, Ungarish (2012) and Sahuri et al. (2015) conducted studies on the interflow density current.
The experiments were conducted in a flume of 8 meters long, 34 centimeters wide and 70 centimeters high. To that end, a solution of water and salt was used to form the ambient fluid with saline stratification and a mixture of water and sediment particles as the dense fluid. 48 experiments were, then, carried out with 4 discharges (1, 1.5, 2, and 2.5 l/s), 3 slopes (2.5, 3.25, and 4 percent) and 4 concentrations (5, 10, 15, and 20 g/l). The motion of the interflow density current in a layered fluid is like that the flow entering the reservoir first expands as an underflow current and after moving a distance, it enters through saline layers of the fluid with saline stratified layers. The current, then, separates itself from the bed at a location in the reservoir where the density of the dense flow equals to that of the layered one. This way, the current finds the suitable density in its environment and moves in a horizontal layer (Fig.1).