Shear Stress in Turbulent Flow over Smooth Surfaces

This paper presents a general equation for shear stress in turbulent flow over smooth surfaces at Reynolds numbers ranging from 2 × 10³ to 6.5 × 10⁵ (based on the boundary layer thickness and the velocity at its edge). The equation is based on a mathematical analysis using the experimental turbulent flow data in a smooth circular pipe as a reference. The general shear stress equation presented here was tested by solving the momentum equation for several surfaces, including a circular pipe, rectangular ducts, flat plates with and without suction, a very long cylinder perpendicular to the stream, and supersonic turbulent flow over a flat plate and along a circular cylinder. It showed good compatibility with the experimental data.