Abstract

The Reynolds shear stress (RS) in zero pressure gradient turbulent boundary layers is established using recently developed composite mean velocity profiles based on the log-law in the overlap region between inner and outer profiles. The contribution of the normal stress difference is also considered and shown to be relatively small. From this analysis, an asymptotic expansion for the maximum RS and its location is developed. The hypotheses underlying this analysis are discussed and the results are compared with experiments and DNS . Using the friction velocity as scale, the RS determined from composite mean velocity profiles agrees reasonably well with low-Re experimental results. However, when comparing with high-Re experiments and DNS , the agreement is generally limited as near the wall the experimental accuracy and resolution becomes problematic and far from the wall the numerical treatment of the boundary condition is very delicate.