THE EVOLUTION OF THE STRATIFIED FLOW STRUCTURE AROUND A WEDGE WITH INCREASING VELOCITY OF MOTION Y.D. Chashechkin 1 , N.F. Dimitrieva 2 1 Laboratory of Fluid Mechanics, A.Yu. Ishlinskiy Institute for Problems in Mechanics of the RAS, 101/1 prospect Vernadskogo, Moscow, 11926, Russia 2 Department of Hydrobionics and Boundary Layer Control, Institute of Hydromechanics of the National Academy of Sciences of Ukraine, 8/4 Zheliabova St., 03680, Kyiv, Ukraine Abstract The 2-D problem on evolution of continuously stratified flow on wedge was investigated. The mathematical model and numerical method of implementation, allowing simultaneous studying all the elements of the internal multi-scale stratified flows was proposed. The constructed original solver of the open-source package OpenFOAM enabled to carry out parallel calculations on stratified flow structure and dynamics around an impermeable horizontal wedge. The evolution of the structure of the stratified flow was studied in a wide range of free stream velocities. Keywords: stratification, wedge, numerical simulation 1 Introduction Nowadays ecological problems have become very acute due to a critical oversaturation of environment with hazardous pollutants and harmful substances due to fast technological evolution of the human civilization. Therefore, the problems on development of techniques for environmental state monitoring and pollution prediction are among the principal tasks of the modern fluid mechanics. A lot of efforts is wasted in attempts of prevention and liquidation of nature- and man-caused emergency situations including wave-nature destructions, i.e. tsunamis, floods, extreme waves, etc., which lead to the most significant damage to the world’s economy and the flow blocking and stagnation causing droughts accumulation of dusts. The natural systems are mostly stratified as a result of the simultaneous effects of the Earth’s gravitation or rotation and media non-homogeneity due to non-uniform distributions in space and time of dissolved matters, gas bubbles, temperature, medium compressibility, etc. [1]. Non-equilibrium medium with molecular flows of stratified admixture is at rest only when the density gradient parallel to the gravity. Very interesting is the fact that a self-induced flow on topography in a stable stratification enables transport of dissolved substances and self-displacement of neutral buoyancy solids in even in the absence of evident external mechanical influences [2]. This widespread phenomenon can be observed at natural conditions and in laboratory experiments in form of horizontal extended streaky structures, which are formed due to interruption of natural diffusion flux of stratifying agent on topography [3 – 5]. Original Schlieren images of self-moving wedge with length 10 cm and height 1.8 cm in the tank felled with the stratified common salt solution are presented in Fig. 1. The wedge body was gently set on the horizon of neutral buoyancy, and then was released from the support. When, after the decay of introduced perturbations, the original density profile with the buoyancy frequency period 7s b T = was restored, the diffusion induced flows, which are the ascending above and descending below of the wedge side, were formed. Under action of deformed pressure gradient, the wedge was set into motion with the speed 0.6 cm/hour. Changes in the color pattern before and past the wedge indicate a general variation of the density profile in the wake past the body and formation high gradient interfaces near the bottom corners. With beginning of the forced body motion the fine structures of diffusion induced flows do not disappear and transformed into just much more complicated and thinner structures such as quasi- stationary high-gradient interfaces separating different types of disturbances, vortex wake and internal waves [6 – 8]. Complex structures, which essentially depend on parameters of the problem (stratification value, obstacle geometry and velocity), are formed at the beginning of the body movement. The studies of the flow past a plate co-directed with the free stream take an important place in hydrodynamics due to the fundamental nature of the problem and important applications. Although the TOPICAL PROBLEMS OF FLUID MECHANICS 79 _______________________________________________________________________ DOI: https://doi.org/10.14311/TPFM.2017.011