Analysis of turbulent, axisymmetric, dense jets discharged to quiescent, uniform or stratified ambients

Abstract

The explicit finite-difference scheme of DuFort-Frankel type which was successfully applied in buoyant jet analysis by previous investigators is now applied to solve partial differential equations of continuity, momentum, energy and salinity to simulate a warm, dense, highly salt-laden jet issuing from desalination plant outfall systems. Turbulent shear stress, heat flux, and component-of-mass flux term appearing in the governing equations are evaluated using an eddy viscosity model which includes effects such as intermittent turbulence near the edge of the jet and buoyancy on mixing. The turbulent Prandtl and Schmidt numbers used to relate to the turbulent exchange of momentum and scalar constituents are kept constant at 0.7 for all calculations reported. The following flow categories are considered: (1) the vertical dense jet discharging into quiescent, uniform or stratified ambient, and (2) the dense jet discharging horizontally or inclined to the horizontal into a uniform or stratified ambient. The predictions of jet trajectory in the lower Froude number range agree favorably with the available experimental data. For higher densimetric Froude numbers, significant deviation between predictions and experiments is observed. However, the experimental data are very limited and additional data are needed before any conclusive remarks can be made.