Velocity distribution and Dip phenomenon in a large amplitude meandering channel

The prediction of the velocity-dip, whereby the location of the maximum velocity occurs below the water surface, could be important for defining the flow pattern and the momentum transport processes. This study explores the dip-phenomenon in a high-curvature meandering bend. With the aid of data collected in a laboratory flume, the influence of the distance to the outer bank, the channel's curvature and the aspect ratio on the formation and position of the velocity-dip is investigated. Results show that, for the aspect ratios examined, a dip forms in the velocity profiles and its position varies along the bend as a function of the channel's curvature and the aspect ratio. Based on the measured data, an equation relating the velocity-dip to the local deflection angle, theta, and the width-to-depth ratio B/h(av) is presented. It has been verified that the values of the velocity-dip estimated by the presented equation are in good agreement with the experimental ones