Experimental Study of Flow Field and Movement of Sediment over a Ramp

Abstract

Applications of hydraulic structures in low dams and diversion structures in countries like India, where sediment is a serious concern, demands a good expanse of research on the flow field and movement of sediment. The present study was focused on the non-uniformity in the velocity distribution along the flow direction and the movement of sediment over a ramp. The velocity distribution of the flow near and over the ramp was studied with the help of Acoustic Doppler Velocimeter. Experiments were conducted to study the mechanics and kinematics of movement of sediment particles. The movement of sediment particles over the smooth ramp was studied with the help of high-speed camera system. The particle velocity, acceleration, applied force and the angle of velocity vector were processed and analyzed from the captured images using digital image analysis techniques. The path of the movement of sediment particle was tracked. The vector results of the flow pattern indicated a very high amount of increase of the uplift velocity (y – component of the instantaneous flow velocity) component over a ramp. The sediment had very little movement for about 3.8 seconds at the beginning of the ramp and accelerated as it moved along the ramp in the downstream side. The path of the sediment movement over the ramp was found to be inclined by 25.6 to 35.7 degree to the horizontal axis which was almost parallel to the ramp (29.055 degree).