Buoyant Jets Discharging Nonvertically Into a Uniform, Quiescent Ambient—A Finite-Difference Analysis and Turbulence Modeling

A differential approach for analysis of turbulent, axisymmetric, buoyant jets and plumes issuing nonvertically into a quiescent, uniform ambient is presented, in which the governing differential equations for conservation of mass, momentum, and energy, derived in a curvilinear, orthogonal coordinate system, are solved by a finite-difference method of the Dufort-Frankel type. This jet configuration is of interest with regard to the design of submerged, offshore outfalls from power plants. The analysis includes consideration of the transverse momentum equation as the jet follows a curved trajectory under the influence of buoyancy forces. The turbulent shear stress and heat flux terms in the governing equations are evaluated through a relatively simple turbulence model which accounts for the effect of buoyancy on the apparent turbulent viscosity through the gradient Richardson number. Predictions for buoyant jets discharging horizontally and at 45 deg to the horizontal are compared with recent experimental data and the results of other prediction methods.