Numerical investigation of plunging density current

When a buoyant inflow of higher density enters a reservoir, it sinks below the ambient water and forms an underflow. Downstream of the plunge point, t he flow becomes progressively diluted due to the fluid entrainment. The ent rainment rate is strongly dependent on the Richardson number and reaches a constant value well downstream of the plunge point. This study is concerned with the analysis of the plunging phenomenon and the determination of the entrainment. A k-epsilon model including buoyancy effects, both in a slopin g and a diverging channel, is used to reproduce the main flow characteristi cs. A relation between the depth at the plunge point in a channel of consta nt width and in a diverging channel is established, and theoretical results for the calculation of the dense layer thickness are provided. The latter indicates that the spreading rate of the dense layer in a diverging channel is a function of both the entrainment rate and the channel width. The pred ictions of the plunge line location are in agreement with most semiempirica l equations.