NEAR-WALL STREAKY STRUCTURE IN A TURBULENT BOUNDARY-LAYER ON A CYLINDER

A near-wall streaky structure has been identified in a turbulent boundary layer on a cylinder in axial flow. A platinum wire looped around a cylinder moving in a tank of quiescent water was used to generate hydrogen bubbles near the wall of the cylinder. The streaks that were visualized correspond to high-speed streaks identified by Kline et al. [J. Fluid Mech. 30, 741 (1967)]. The appearance, motion, and spacing of the streaks appear similar to the streaky structure in a planar boundary layer, suggesting a similarity in the mechanism for the generation of turbulence in the boundary layers on a flat plate and on a cylinder.