11th World Congress on Computational Mechanics (WCCM XI) 5th European Conference on Computational Mechanics (ECCM V) 6th European Conference on Computational Fluid Dynamics (ECFD VI) E. Oñate, J. Oliver and A. Huerta (Eds) NUMERICAL AND LABORATORY EXPERIEMTS OF STABLY STRATIFIED FLOW AROUND AN OBSTACLE HATEM HOUCINE 1 ,* , JOSE M. REDONDO * , OTMAN BEN MAHJOUB 2,†,* ADEL GHARBI 1 , YULI D. CHASHECHKIN 2 AND PHILIPPE FRAUNIE † 1 Laboratoire de Mécanique des Fluides, Faculté des Sciences de Tunis, Université El Manar, 2092 Tunis, Tunisie. email: hatem_houcine@yahoo.fr * Departament Fisica Aplicada , Universidad Politécnica de Cataluña (UPC) Campus Norte UPC, 08034 Barcelona, Spain e-mail: redondo@fa.upc.edu , www.upc.com 2 Institute for Problems in Mechanics of the Russian Academy of Sciences, Moscow, Russia, e-mail: chakin@ipmnet.ru † Mediterranean Institut of Oceanography (MIO) Univ. Sud Toulon Var, La Garde CEDEX, France email: fraunie@univ-tln.fr , http://mio.pytheas.univ-amu.fr/ Key Words: Turbulent mixing, Stratified flows, Internal Waves, LES methods. Abstract. This paper describes a numerical study of the two dimensional flow of a linearly stably stratified fluid around a body (vertical or horizontal thin strip) towed horizontally at constant velocity . The dimensionless parameters governing this problem are the internal Froude number  =   ⁄ , the Reynolds number ℜ =   ⁄ , the ratio of intrinsic length scales  =  ⁄ and the Peclet number  =    ⁄ (L is the dimension of the strip; N is buoyancy frequency,  is stratification length scale,  is kinematic viscosity and   is the solute diffusivity). The set of the dimensionless parameters define both the conditions of numerical and of small scale laboratory modeling of environmental flows. The Fields of velocity, density and their gradients were computed and visualized as well as the wave internal propagation. Measurements on velocity structure functions and the effect of wave- turbulence interaction on mixing and intermittency are used to describe the topology of the flow showing the relationship between the Richardson number and the blocked wake thickness. 1 INTRODUCTION This paper describes a numerical study of the two dimensional flow of a linearly stably stratified fluid around a body (vertical or horizontal thin strip Lb or h ) towed horizontally at constant velocity U. The major dimensionless parameters governing this problem are the internal Froude number, the Reynolds number, the intrinsic relevant length scales and the