INVESTIGATION OF REYNOLDS STRESS STRUCTURES IN PLANE TURBULENT WAKES.

Abstract

Instantaneous u-v signals in the turbulent far wake of a cylinder have been analysed using an extended 'quadrant analysis' in order to investigate the Reynolds stress structure and the features of large eddies. The results indicate that the region between the location of maximum shear and the edge of the wake is similar to the outer layer of boundary layers and bursts of slow moving flow ejecting outward contribute the most to the Reynolds shear stress. In the wake centerline region, fast moving fluid crossing the centerline contributes significantly but with opposite sign. There is a special type of flow near the centerline: flow moving upstream along the centerline slower than the mean velocity. This type of motion does not contribute to the shear stress but contains kinetic energy.