Distribution of reynolds shear stress in steady and unsteady flows

This study investigates the Reynolds shear stress distribution in steady and unsteady non-uniform flows. Specifically, it deals with how to express the deviation of this turbulence characteristic from that of uniform flow line; it is found that flow acceleration can well represent the deviation of Reynolds shear stress from its standard linear distribution. By connecting the flow acceleration with Reynolds shear stress, the study demonstrates empirically that the linear distrubiton of Reynolds shear stress can be observed when the flow acceleration is zero; the concave distribution of Reynolds shear stress can be observed when the flow acceleration is negative or when the flow velocity is decreased along the channel; the convex distribution of Reynolds shear stress can be observed when the flow acceleration is positive or the flow velocity is increased along the channel. These empirical results have been verified using published experimental data and good agreement between the predicted and observed profiles has been achieved.