10H50 : n° 520 Stratified turbulence in coastal flows

Philippe Fraunié
LSEET UMR 6017
The turbulent diffusion in the coastal flow has been investigated from in situ and numerical experiments. A Lagrangian measurement approach for vertical profiles of temperature, salinity and momentum were used to parametrize the turbulent mixing as related to the local Richardslon number, using optimal control techniques. High order numerical modelling, including Large Eddy Simulations, allowed to explain secondary flows and filaments as observed from HF Doppler radar and satellite imagery.

11H10 : n° 1296 Dynamique d'un tourbillon fortement incliné dans un fluide stratifié

Patrice Meunier Nicolas Boulanger Stéphane Le Dizès
Institut de Recherche sur les Phénomènes Hors Equilibre
Nous nous intéressons expérimentalement à la dynamique d’un vortex incliné dans un fluide stratifié. Nous avons généré un tourbillon de pale dans une cuve stratifiée. Ce vortex possède un rayon critique pour lequel de fortes vitesses axiales sont générées, si la vitesse angulaire du vortex est suffisamment importante. La structure de cette couche critique est prédite théoriquement. Ces vitesses axiales déstabilisent le vortex très rapidement et créent un très fort mélange.

11H30 : n° 1380 From baroclinic instability to developed turbulence

Claude Cambon Guillaume Simon Fabien Godeferd Aziz Salhi
Laboratoire de Mécanique et d’Acoustique
The coupled effects of mean shear, density-stratification and system rotation are investigated in the context of strong turbulence, i.e. accounting for the baroclinic instability. Although there exists a large literature in the rotating shear case and the stratified shear case, with linear approaches, Direct or Large Eddy Simulations, very few studies consider the combined three ingredients in the context of distorted homogeneous turbulence.

11H50 : n° 1050 Internal gravity waves breaking above Great Meteor Seamount

Louis Gostiaux Hans van Haren
LEGI
We present a 19 days, high frequency record of temperature profiles above the eastern shelfbreak of the Great Meteor Seamount. Seamounts are known to be efficient regions for internal tides generation, but also participate in mixing and transport through nonlinear processes and wave breaking. We measured extreme overtuning events associated with the upgoing tidal flux pushing cold water up the slope. Strong shear also lead to small scale instabilities that are also resolved by our sensors.