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Accueil > Grands équipements > La plateforme tournante Coriolis > Projets de recherche > Archives 2004

Turbulent vortex dipoles in a shallow water layer

Damien Sous, Natalie Bonneton, and Joël Sommeria,Phys. Fluids 16, 2886 (2004)

This paper describes an experimental study on turbulent dipolar vortices in a shallow water layer. Dipoles are generated by an impulsive horizontal jet, by which a localized three-dimensional turbulent flow region is created. Dipole emergence is only controlled by the confinement number C5AQ/H2tinj whereas the jet Reynolds number Re5AQ/v has no influence in the studied range 50 000,Re,75 000 H is the water depth, v is the kinematical viscosity, Q the injected momentum flux and tinj the injection duration !. When C.2, the flow becomes quasi-two-dimensional and a single vortex dipole emerges in most cases. By qualitative observations and application of particle image velocimetry, the main dipole features have been determined. The shallow water dipoles are characterized by the simultaneous presence of several scales of turbulence : A quasi-two-dimensional main flow at large scale and three-dimensional turbulent motions at small scale. A vertical circulation takes place in the dipole front. A theoretical model is presented and compared to experimental results. The three-dimensional turbulence production occurs mainly in the frontal circulation. A good agreement has been found between the model prediction and the measurements for the velocity evolution. © 2004 American Institute of Physics.