3D numerical simulation of ambient discharge of buoyant water

Waste heat and wastewater are frequently discharged into ambient water and become intermittent sources of buoyancy. In order to control and reduce the environmental impact of these discharges, the mixing characteristics of such discharge in ambient flow should be determined. In this work the transport, mixing and turbulence characteristics of intermittent discharge of buoyant fluid in ambient flow are simulated by a 3D numerical model incorporating a buoyancy extended k-ε model for turbulence. In the numerical model the governing equations are split into three parts in the finite difference solution: advection, dispersion and propagation. The advection part is solved by a characteristics-based scheme. The dispersion part is solved by the central difference method and the propagation part is solved implicitly by using the Gauss-Seidel iteration method. The model has been applied to cases of instantaneous and continuous discharges of buoyancy in ambient water with or without current. Dimensional analysis is used to estimate the initial values. The estimated range of values are found not sensitive to the solution. Satisfactorily comparison between computed results and the experimental results is achieved for the trajectories and lateral widths of the buoyant discharge. The engineering applicability of the model is thus ascertained.