Study of leading-edge dual-tapered submerged vanes for vortex lift-augmented sediment control in rivers

ABSTRACT The flow around the tapered submerged vanes is characterised by the interaction of the leading-edge vortex (LEV) with the boundary layer, especially at high angles of attack. An LEV creates its own low-pressure zone on the suction side of tapered submerged vanes, augmenting vortex lift. The leading-edge shape of submerged vanes controls vortex formation and lift distribution by influencing boundary layer separation. This study examines how dual-tapered vane arrangements enhance vortex lift near the bed to deflect sediment, while increasing potential lift farther from the bed to generate the strong secondary circulation and reduce near-bed turbulent energy downstream, promoting sustained sediment accumulation. Therefore, two different tapering angles (18° and 33.7°) were utilised at various locations of the leading edge of the submerged vanes. Moment of momentum (M.O.M.), near-bed vorticity, and near-bed transverse velocity were evaluated for different configurations of submerged vanes. The best model configuration was β5, with the bottom two-thirds of the leading edge tapered at 18° and the upper one-third at 33.7°. This configuration exhibits a 34.3% higher M.O.M. in the near-bed region than classical rectangular submerged vanes. It produces significant vorticity near the riverbed, potentially enhancing the efficiency of riverbed dredging operations.