Wall shear stress determination from near-wall mean velocity data in turbulent pipe and channel flows

A novel method is proposed that allows accurate estimates of the local wall shear stress from near-wall mean velocity data in fully developed pipe and channel flows. DNS databases are used to demonstrate the accuracy of the method and to provide the reliability requirements on the experimental data.To demonstrate the applicability of the method, near-wall LDA measurements in turbulent pipe and channel flows were performed. The estimated wall shear stress is shown to be accurate to within 1%. Streamwise mean velocity and turbulence intensity profiles normalized with the wall friction velocity at several Reynolds numbers are presented.The current research was funded in part by the European Community under the BRITE-EURAM program, Deutsche Forschungsgemeinschaft (Du 101/16-1,2) and Deutscher Akademischer Austauschdienst. The authors are also grateful to Professors F. Nieuwstadt, N. Kasagi, P. Moin and Drs. J. Kim and N. Gilbert for providing their direct simulation data.