Study on the Effect of Different Bed Sills on Flow Structure and Scouring At the Bed of Channel

Abstract

Stabilizing the banks and bed of the river is one of the most important problems in river engineering. This importance arises from the scouring of the banks and bed of a river impacting on hydraulic structures and the aquatic environment. In this study, both experimental and numerical techniques were employed to analyse concave, convex and sine bed sills. It was found that in concave bed sill vortices develop at the banks and transfer sediment particles to the middle of the channel, conversely in a convex bed sill vortices develop at the centreline and move sediment to the banks. The experimental results also confirmed that the maximum scouring depth occurred at locations where vortices develop for the concave and convex bed sills. This caused stability of the channel centreline for concave bed sill when compared to the convex bed sill. Result for convex bed sill showed stabilization at the banks by creating minimum depth of scouring at the banks of the channel. Since both concave and convex bed sills stabilize bed at centreline or banks only, a sine bed sill is also proposed in this study to protect both banks and centreline. The sine shape bed sill was also tested in this study and the results showed that it is very effective for the stability of both centreline and banks.