Secondary Flow, Shear Stress and Sediment Transport

Abstract

A mathematical modeling and computational technique is presented which is capable of treating and dealing with interactions among hydraulic variables is open channel flows, such as the distribution of primary flow velocity, channel cross section, discharge rate, secondary flow, shear stress, and sediment concentration. A shear stress formula is presented that can include the effect of secondary flow. The formula gives peak values of boundary shear that occur on the channel bottom near the corners and on the side walls. Such peak values of boundary shear are owing to the momentum transfer to the region by secondary flow. The simulation technique can be used as a decision-making tool in selecting engineering designs and controls for channel protections. The main role of secondary flow in sediment transport seems to be to transport sediments in the transverse direction, whereas the gravity brings sediments downward and the diffusion brings sediment particles upward. The vertical component of secondary flow seems to help gravity bring sediment down in most of the area in a transverse cross section of a channel.