Investigating Particle-Laden gravity currents using the Light Attenuation Technique
Particle-laden gravity currents (PLGCs) such as turbidity currents are commonly encountered in estuaries where rivers discharge sediments into the oceans. In the process, they are involved in the transport of (micro)-plastics from the coast toward the deep ocean. The dynamics of PLGCs are largely controlled by the properties of the particles that drive them, such as their density, size - and hence their settling velocity - and geometry.
While the mean flow properties in dilute regimes have been largely studied, the distribution of particles in the flow and their relation to the PLGC dynamics in larger concentration regimes is still poorly known.
In this talk, I will present experimental results on the dynamics, mixing, and transport properties of PLGCs. Experiments have been carried out in a lock-release configuration in which the initial particle volume fraction and buoyancy are carefully controlled.
I will introduce the principle of an extended light attenuation technique (Particle Induced Light Attenuation Technique or PILAT) that provides access to novel quantitative measurements of the particle mass fraction field. The influence of the initial particle concentration on the turbulent dynamics of the flow and the front velocity are evaluated and will be discussed.
This study is part of a larger collaborative project PALAGRAM -Particle Laden GRAvity current Modelling- involving three complementary experimental and one numerical configuration. I will finally summarize the results of an extensive study of the slumping regime in which the respective role of particle settling properties volume fraction and bottom slope have been highlighted.
Contact Nathanaël Machicoane for more information or to schedule a discussion with the seminar speaker.