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The interactions between turbulent penetrative convection and gravity waves: from laboratory experiments to geo- and astrophysical applications (COWAVE)
Date du début: 1 sept. 2012, Date de fin: 31 août 2014 PROJET  TERMINÉ 

"In many geo and astrophysical situations, a turbulent convective fluid layer is separated from a stably stratified one by a relatively sharp interface. Examples include the oceanic upper mixed layer and underlying pycnocline zone, the atmospheric convective layer and overlying stratosphere, the convective and radiative zones in stars. In classical models, stratified zones are often postulated to be motionless. But it has been recognized that gravity waves generated at the convective interface by turbulent motions could be of fundamental importance regarding momentum and energy transport through the stratified layer, with global consequences on the system evolution. Despite several studies, the current treatment of convectively generated gravity waves still presents major weaknesses. Indeed, their generation mechanism, their typical amplitude, their time and space frequency spectra, and the amount of energy and momentum that they carry remain largely unknown. Besides, the action of global rotation (omnipresent in natural systems) has not been accounted for. The purpose of this project is to go beyond the state-of-the-art in investigating these questions experimentally, using the most recent technics of flow measurements. Simplified set-ups will be developed at the laboratory scale, keeping the main physical ingredients of natural configurations, and addressing all their interactions and non-linearities simultaneously, which is barely accessible to theory and numerics. Generic laws will be derived and validated, before being applied to stars, oceans and atmosphere. This project is by its essence interdisciplinary, lying at the frontier between fluid mechanics and geo/astrophysics. From our original approach, we envisage to find new horizons regarding the dynamics of mixed convective/stratified systems, of direct interest for practical and fundamental applications (e.g. parameterization in general circulation models for weather predictions, model of the Sun interior)."