Characteristics of Turbulent Boundary Shear Stress

by Paul H. Blinco, (A.M.ASCE), Res. Hydr. Engr.; U.S. Dept. of Agr., Oxford, MS,
Daryl B. Simons, (F.ASCE), Prof. and Assoc. Dean for Engrg. Res.; Coll. of Engrg., Colorado State Univ., Fort Collins, CO,

Serial Information: Journal of the Engineering Mechanics Division, 1974, Vol. 100, Issue 2, Pg. 203-220

Document Type: Journal Paper


The results of limited measurements of the instantaneous boundary shear stress in smooth boundary, free surface flows are presented. A commercially available, flush surface, hot-film sensor with a constant temperature anemometer was used. The statistical moments, probability density functions and autocorrelation curves of the boundary shear stress process were directly obtained by digital computer. The time-analysis at shear stress data revealed the following information: (1) the relative boundary shear stress turbulence intensity, the ratio of the root mean square to the mean decreased with increasing Reynolds numbers; (2) the probability density function of the instantaneous boundary shear stress is a non-Gaussian, positively skewed, Reynolds number dependent distribution; (3) the autocorrelation functions indicate that the boundary shear stress process is not composed of periodic components; and (4) the relative macroscale of the turbulent boundary shear stress to the viscous sublayer thickness was found to increase with increasing Reynolds number.

Subject Headings: Dilatancy | Boundary shear | Shear stress | Shear flow | Reynolds number | Flow measurement | Free surfaces | Overland flow

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