Analysis of plunging phenomenon in dam reservoirs using three-dimensional density flow simulations

Abstract

Density flow is investigated in a three-dimensional model through a dam reservoir with diverging and sloping bottom channels. When an inflow of higher density enters ambient dam reservoir water, it plunges below the ambient water and becomes density underflow. In the present model, nonlinear and unsteady continuity, momentum, energy, and turbulence model equations are formulated in the Cartesian coordinates. The k–ε turbulence model is used with an extension to include production or destruction of turbulent kinetic energy. To investigate the Coriolis force effect on the density flow in a dam reservoir, a Coriolis force parameter is included in the governing equations. The equations of the model are solved based on the initial and boundary conditions of the dam reservoir flow for a range of bottom slopes and divergence angles. In this paper, variation in density flow parameters, such as velocity, temperature, and turbulence viscosity through the dam reservoir, is investigated. Moreover, mixing rate, plunging points, and plunging depths are determined from the simulation results. The results of the present model are compared with the previous experimental work and model. The present model results follow the expected basic trend. The three-dimensional model simulation and analysis improve the understanding of density flow, underflow, divergence flow, mass transport, and dam–reservoir flow interaction.