Direct Derivation of Streamwise Velocity from RANS Equation in an Unsteady Nonuniform Open-Channel Flow

Abstract

This study investigates the vertical profile of streamwise (longitudinal) velocity in an unsteady and nonuniform open-channel turbulent flow. In contrast to the previous works, a direct derivation for velocity distribution starting from Reynolds-averaged Navier-Stokes (RANS) equation has been shown. Due to unavailability of several expressions for unsteady flow to solve the governing equation, a few assumptions have been made. The proposed model contains the effect of secondary current, which is generally present in all types of open-channel flow. The resulting partial differential equation has been solved numerically. Validation has been done by comparing the model with available experimental data and an existing analytical model.