Scaling properties of dense water overflows on a continental slope

Abstract

Dense overflows on a continental slope play an important role in renewing deep water as part of the global thermo-haline convective cycle of the oceans. We report here laboratory experiments reproducing this phenomenon on the large 'Coriolis' turntable in Grenoble, providing good dynamical similarity with the oceanic case. The gravity current is created by salty water injected with a constant flux, which flows down the incline slope (2m wide, 10m long, 15 degrees of inclination) with intense turbulent mixing. It is deviated by the Coriolis force to a cross-slope horizontal direction. We study both the cases of a homogeneous and density stratified ambient fluid. Velocity fields are measured by particle image velocimetry (PIV). Density profiles are also measured to determine the width, thickness and position of the gravity current, and to measure the mixing process. A self-similar behaviour is observed generalizing results for turbulent self-similar plumes and jets to this situation.