Lift off and turbidity currents in the environment

Abstract

This contribution presents an experimental investigation on the behaviour of sediments in a turbulent boundary layer flow, it compares the energy and vorticity needed to generate a turbidity current and the zero mean flow lift off and entrainment across a stably stratified density interface, either produced by solutes, sediment concentration or both. The experimental parameters are used to quantify the entrainment, the mixing efficiency and different types of dominant instability and the topological aspects of the turbulent cascade in the environment. The experiments allow to detected both horizontally and vertically. The local sediment and velocity fields. Grid turbulence in an enclosed two layer system is measured with PIV as well as with sonic velocimetry. Observations of the horizontal and vertical velocity energy spectra as well as the structure functions are used to estimate local mixedness, entrainment and intermittency.