A NUMERICAL-MODEL OF THE FLUID MOTION AT A DENSITY FRONT IN THE PRESENCE OF BACKGROUND TURBULENCE

The effects of background turbulence on gravity currents produced by l ock exchange are investigated using a numerical model with the aim of understanding the fluid motions associated with coastal fronts. It is shown that, at high turbulence intensities, the mutual intrusion of gr avity currents is inhibited and the horizontal mass transport is domin ated by the turbulent diffusion. The propagation of the front, the hor izontal density flux, and the potential energy anomaly are calculated and are compared with available experimental data. The model is extend ed to include the effects of background rotation. It is found that, in the presence of background turbulence, the geostrophic equilibrium ca nnot be achieved, and the cross-frontal velocity persists indefinitely . The effects of rotation on the fluid motions were found to be impair ed by the background turbulence.