Characteristics of secondary flow vorticity and longitudinal velocity in a sharp bend

Abstract

The complex flow structure in sharp bends may cause a series of water and sediment problems which are of great risk to flooding control and engineering safety. For this reason, there is of great significance to study the characteristics of secondary flow in sharp bends. In this article, the characteristics of vorticity and longitudinal velocity in sharp bends are studied by laboratory experiments and theoretical analysis. The results showed that there are two opposite circular currents on every cross-section in the bend. The two circular currents show a trend of increasing and decreasing streamwise. Vorticity is used to indicate the secondary flow intensity and is used to adjust the formula of longitudinal average velocity. The new formula fit the experiment data well and can describe the phenomenon of the maximum longitudinal average velocity appearing near the bed surface.