PIV-PLIF Characterization of Nonconfined Saline Density Currents under Different Flow Conditions

Abstract

Saline density currents are a growing environmental concern due to their increasing occurrence generated by brine discharges. The present paper shows an experimental global characterization of the quasi-steady-flow properties of nonconfined saline currents using nonintrusive particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques. This global characterization includes the study of the influence of the bottom slope and the initial flow conditions such as the flow rate, the thickness, and the saline concentration on the plume behavior. The results achieved reveal the self-similarity of the mean variables’ vertical profiles and the collapse of higher length scales of turbulence along the density currents. In addition, this study finds the existence of a normal flow state from which the vertical mixing becomes the main mixing mechanism in the plane of symmetry of the currents. Finally, a comparison between widespread numerical integral approximations and the measured data reveals that these approximations need to be reformulated. The high-quality database presented in this study is a key tool for future calibration and validation of different numerical approximations.