Finite volume gravity currents impinging on a stratified interface

An experimental study of two-dimensional gravity currents impinging on a stratified interface in a two-layer stratified environment is presented. The gravity currents are created by the release of a fixed volume of dense fluid along a 6 degrees slope. The effect of the stratified interface on the entrainment and mixing processes is quantified by the use of planar laser induced fluorescence. Moreover, to understand the entrainment process and to quantify the effect of the impingement on the internal structure of the gravity current, particle image velocimetry measurements are performed. Both instantaneous velocity and vorticity fields are quantified and averages are computed over 0.2 s. The measurements are centered on the impact region between the gravity current and the stratified interface. In previous experiments we have determined the entrainment rate and studied the internal structure for a gravity current created by a continuous source under the same experimental conditions. A thorough comparison of the two cases is provided.