Effect of Inflow Froude Number on Flow Pattern in Channel-Expansive Transitions

Abstract

Channel expansions are common in both natural and artificial open channels. With increasing cross-sectional dimensions in an expansion, flow decelerates. Because of the complexity of flow patterns, physical models alone cannot provide a clear understanding of the physics governing the flow field and it is necessary to study this phenomenon not only in the field and experimentally but also numerically. In this study, the flow pattern in an expansive transition was numerically simulated. For simulating turbulence characteristics, a Reynolds stress model was used in addition to continuity and Navier-Stokes equations. Water surface and velocity profiles at different sections of transition were compared with experimental results and showed good agreement. After calibration, the model was run to consider the effect of inflow Froude numbers on turbulent kinetic energy and bed-shear stress at different cross sections. The results show that increasing the inflow Froude number increases turbulent kinetic energy and bed-shear stress.