Flow Pattern and Erosion in a 90-Degrees Sharp Bend around a W−Weir

Abstract

Different flow-altering methods, such as W−Weirs, have been developed to reduce erosion. For this study, we performed two experiments: (1) installing a W−Weir in various positions to determine the best angle for placement, and (2) investigating the variation of flow patterns and bed shear stress distribution in a 90-degree sharp bend by measuring the 3D components of flow velocities, with and without W−Weirs, where the greatest scour depth occurs. The results from the three installation angles indicate that less scour depth and volume of sediment removal occur when the weir is located close to the end of a bend. In addition, the value of the secondary circular power without a weir was higher than the position with a weir; however, this value significantly increased at 70 degrees due to turbulence flow near the W−Weir. This secondary flow power reduction at 45 degrees with a W−Weir increased by 65.8 percent for a Froude number value of 0.17, and by 29.8 percent for a Froude number value of 0.28, compared to values without the W−Weir, respectively.

Keywords

• W−Weir
• 90-degree bend
• secondary flow
• shear stress
• erosion
• flow pattern