Reynolds-number scaling of the flat-plate turbulent boundary layer

Despite extensive study, there remain significant questions about the Reyno lds-number scaling of the zero-pressure-gradient flat-plate turbulent bound ary layer. While the mean how is generally accepted to follow the law of th e wall, there is little consensus about the scaling of the Reynolds normal stresses, except that there are Reynolds-number effects even very close to the wall. Using a low-speed, high-Reynolds-number facility and a high-resol ution laser-Doppler anemometer, we have measured Reynolds stresses for a ha t-plate turbulent boundary layer from Re-theta = 1430 to 31 000. Profiles o f (u'(2)) over bar, (v'(2)) over bar, and (u'v') over bar show reasonably g ood collapse with Reynolds number: (u'(2)) over bar in a new scaling, and ( v'(2)) over bar and (u'v') over bar in classic inner scaling. The log law p rovides a reasonably accurate universal profile for the mean velocity in th e inner region.