2 차원 수직벽을 지나는 재부착 박리 전단층의 난류구조에 관한 연구 (I)

Abstract

초록

Hot-wire measurements of second and third-order mean products of velocity fluctuations have been made in the separated, reattached, and redeveloping boundary layer behind a vertical fence. Mean velocity, wall static pressure distributions have also been measured in the whole flow field.Upstream of the reattachment point, the separated shear layer develops as a free mixing layer, but the gradient of the maximum slope thickness, turbulent intensities and the Reynolds shear stress are higher than that of the mixing layer due to initial streamline curvature and the effects of highly turbulent recirculating flow region.In the reattachment region, Reynolds shear stress and triple products decrease mainly because of the confinement of the large eddies by the solid wall.In the initial stage of the redeveloping boundary layer, the decrease of triple products near the surface is far more rapid than the decrease of the shear stress; that is the presence of the solid wall has a marked effect on the apparent gradient diffusivity of intensity or shear stress and throws doubts upon the usefulness of the simple gradient diffusivity model in this region.