Numerical Prediction of Vertical Turbulent Exchange in Stratified Flows

摘要

The development of a mixed density layer in a stratified saline water flow was studied for different initial and boundary conditions in order to determine the dimensionless entrainment velocity as a function of an overall Richardson number. The mathematical model is based on the conservation laws for momentum and salinity. A two-equation turbulence model is used for the determination of exchange coefficients. A sensitivity study indicates that the turbulent Prandtl number for salinity and the buoyancy term in the equation determining the turbulent length scale are very influential. Suggestions for these terms are presented. A comparison between predictions and measurements of the laboratory flow considered supports the mathematical formulation put forward.