A Numerical Model of the Fluid Motion at a Density Front in the Presence of Background Turbulence

Abstract

The effects of background turbulence on gravity currents produced by lock 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 gravity currents is inhibited and the horizontal mass transport is dominated by the turbulent diffusion. The propagation of the front, the horizontal density flux, and the potential energy anomaly are calculated and are compared with available experimental data. The model is extended to include the effects of background rotation. It is found that, in the presence of background turbulence, the geostrophic equilibrium cannot be achieved, and the cross-frontal velocity persists indefinitely. The effects of rotation on the fluid motions were found to be impaired by the background turbulence.