Distribution of Wall Shear Stress in Right-Angle Branches during Laminar Flow

Abstract

The distribution of wall shear stress and velocity in laminar steady flow has been experimentally studied in a model right-angle branch, in which the side branch bifurcates at a right-angle from the trunk. The branch model has a radius of curvature at the upstream corner and a square edge at the downstream corner. The wall shear stress was measured with an electrochemical method, and the velocity profile was measured by using laser Doppler anemometry (LDA). Near the upstream corner, along the proximal wall the wall shear stress has the form of a large-amplitude, damped sine wave. At the upstream corner, the amplitude of the wall shear stress increases markedly with decreasing the radius of curvature. The damped sinusoidal variation of wall shear stress along the proximal wall is one of the characteristic flow structures in right-angle branches. Also, the wall shear stress measured with the electrochemical method is compared with that estimated from the velocity profile measured by using LDA.