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Accueil > Grands équipements > La plateforme tournante Coriolis > Projets de recherche > Archives 2005

Transition from deep to shallow water layer : formation of vortex dipoles

Damien Sous, Natalie Bonneton, Joel Sommeria,European Journal of Mechanics B/Fluids 24 (2005) 19\u201332

In this paper we study the transition from a deep to a shallow water layer and the formation of quasi-two-dimensional vortex dynamics. Vortices are experimentally generated by a circular horizontal turbulent pulsed jet. The dimensional analysis gives two relevant dimensionless parameters : the jet Reynolds number Re and a number C which characterizes the vertical confinement. They are respectively defined by Re = \u221aQ/\u03bd and C = (\u221aQ/H2)tinj (H is the water depth, \u03bd is the kinematical viscosity, Q the injected momentum flux and tinj the injection duration). Experimental results show a strong influence of C on the flow : when C <1, the evolution is a typical three-dimensional turbulence decay, while when C >2 we observe the formation of large vortex dipoles. However these dipoles are not strictly two-dimensional because of the presence of a vertical circulation in the front of the dipole. Results are independent of the jet Reynolds number in the range 1000 < Re < 1800. In addition, a comparison between experimental shallow water dipoles and theoretical model is exposed. \uf6d9 2004 Elsevier SAS. All rights reserved.