DYNAMICAL CHARACTERISTICS OF COHERENT STRUCTURE IN THE OUTER REGION OF TURBULENCE BOUNDARY-LAYER

In the present paper the coherent structures in the outer region of tu rbulent boundary layer were investigated experimentally and analytical ly. From the observation of the how field over smooth wall, rough wall and sand wave wall, it was found that the direct effect of wall on th e flow structure can reach y(+1) approximate to 100, and both lateral and vertical vortices exist in the outer region, but the coherent stru ctures in the outer region are mainly the formation, development and d ecay of the large-scale lateral vortices. By experimental and dynamica l analysis, some influence factors and their relations associated with the dynamical process of lateral vortices were deduced.