EXPERIMENTAL STUDY OF DYKE FORMATION USING SUBMERGED VANES

Abstract

Submerged vanes are thin rectangular-shaped low-profile foils, typically set at small angles to the main current and arranged in either single or multiple parallel arrays in the longitudinal direction. When installed in a channel bend they induce a helicoidal vortex that interacts with and weakens the centrifugally induced secondary current. The latter effect leads to reduced local erosion near the bend's outer bank. Physical model testing was performed to determine the effects of several parameters affecting submerged vane performance, including submerged vane height H, length L, angle to main flow direction a, vane streamwise spacing 8s, vane transverse spacing from outer bank S n. Submerged vanes effectively stabilize channel bend erosion by reducing the scour depth at the outer bank, generating positive transverse bed slope at the outer bank, and by reducing the net sediment loss through the channel. Increasing capital costs, emerging environmental concerns and rising maintenance expenses of the conventional river training works around the world have led to the development of submerged vanes in practice. In the last two decades, there has been an increase in the use of submerged vanes as sediment management devices as opposed to the traditional sediment control structures. Smaller vane dimension and the relatively better alignment with the flow field compared to conventional structures lead to the required modification of the flow field at less flow resistance and low structural as well as low maintenance cost and these are some of the reasons behind their increased popularity.