REEXAMINATION OF THE REYNOLDS-NUMBER-EFFECT ON THE MEAN FLOW QUANTITIES IN A SMOOTH WALL TURBULENT BOUNDARY-LAYER

Measurement of the local skin friction coefficient and re-examination of the Reynolds-number-effect on the mean flow quantities were made in a zero-pressure gradient, smooth wall, turbulent boundary layer. In o rder to do this fairly, the two-dimensionality of the flow field was c arefully adjusted. And, the wall shear stress tau(w) was determined by direct measurement using a floating element device. The Reynolds numb er based on the momentum thickness R-theta = U-1 theta/nu ranges from 840 to 6 220. The present experimental results of c(f) propose a new e mpirical formula which well represents the present experimental data a nd confirms that the Karman constant kappa = 0.41, which implies a slo pe of the logarithmic linear layer, is independent of Re down to R-the ta = 860, whereas the additive constant varies with R-theta. The magni tude of the wake parameter takes an asymptotic value of 0.62 if the Re ynolds number is sufficiently high. The effect of R-theta on all the t urbulent intensities is evident even within the viscous sublayer. The constant stress layer does exist in the Reynolds shear stress profiles despite that the constant value varies with R-theta.