THE TURBULENT NEAR WAKE OF A FLAT-PLATE AT LOW REYNOLDS-NUMBER

Mean-velocity and turbulence measurements have been made in the turbulent near wake of a flat plate at various Reynolds numbers in order to investigate the low-Reynolds-number effects in this region. The results indicate that the low-Reynolds-number effects are significant enough to partially explain the discrepancies in the existing mean-velocity data. It has been found that, while the Reynolds-number-independent, inner-law similarity of the boundary layers continues to exist, the width of the inner wake that develops within the inner-law region scales with the outer variable. Therefore, the mean velocity near the wake centreline depends on the Reynolds number. It is conjectured that this is due to the influence of the large eddies of the outer laver on the spreading of the inner wake. Measured turbulence quantities indicate that sudden changes occurring jusl downstream of the trailing edge are independent of the Reynolds number, but the subsequent development of the turbulent stress profiles depends on the Reynold number. The Reynolds shear stress and the mean-velocity profiles within the innei wake show approximate similarity. © 1990, Cambridge University Press. All rights reserved.