Analytical Study of Scour Mechanism Around Immersed Rectangular Vane Structures

Abstract

The intricacy of sedimentation and its transport in alluvial channels is a matter of great apprehension in the arena of hydraulic engineering. In this perspective, a submerged vane plays a dynamic part by providing an effective and efficient solution of sediment management. An immersed vane structure acts as a vortices-generating contrivance that can be employed for controlling the channel bed erosion in streams. The flow pattern downstream of the vane can be transformed by fixing the vanes on the stream bed at a certain angle, resulting in the modification of shear stress and sediment redistribution on the channel bed. Immersed vanes have found numerous functions in channel hydraulics, but commonly, immersed vanes are applied to generate optimal riverbed depth, to diminish unnecessary scour or sediment deposition, and an overall improvement of navigability. In the present study, four clearwater experiments are performed using rectangular single, double, and triple vanes arrangements to analyze the equilibrium scour pattern around the vanes positioned at 15⁰ angle of attack The contours of scouring holes developed around the immersed vanes are plotted. From the evaluation of the scour geometries and contours morphology around such arrangements of submerged vanes, it is observed that for each set of arrangement, there is a variation in the scour formation in the upstream and downstream side of the flow, which in turn gives a clear idea about the scour patterns around them. The scours are observed to be more for the downstream vanes in the case of multiple vanes in comparison with a single vane. The horseshoe vortex and wake vortex are much stronger at the place near to the vane. The experimental study provides an insight into the proper design and placement of vanes which could be further utilized for more effective channelizing of sediments toward the bank, enhancing the navigability of the channel.