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Accueil > Équipes > Equipe MEIGE : Modélisation, Expériences et Instrumentation pour la Géophysique et l’Environnement > Diffusion scientifique > Séminaires internes

Linear stability analysis of particle-laden hypopycnal plumes

08/02/2018 - Jorge Hugo Silvestrini

Gravity-driven riverine outflows are responsible for carrying sediments to the coastal waters. The
turbulent mixing in these flows is associated with shear and gravitational instabilities such as Kelvin-
Helmholtz, Holmboe, and Rayleigh-Taylor. Results from temporal linear stability analysis of a
two-layer stratified flow are presented, investigating the behavior of settling particles and mixing
region thickness on the flow stability in the presence of ambient shear. The particles are considered
suspended in the transport fluid, and its sedimentation is modeled with a constant valued settling
velocity. Three scenarios, regarding the mixing region thickness, were identified : the poorly mixed
environment, the strong mixed environment, and intermediate scenario. It was observed that Kelvin-
Helmholtz and settling convection modes are the two fastest growing modes depending on the particles
settling velocity and the Richardson number. The second scenario presents a modified Rayleigh-
Taylor instability, which is the dominant mode. The third case can have Kelvin-Helmholtz, settling
convection or modified Rayleigh-Taylor modes as the fastest growing mode depending on the
combination of parameters.