Author(s): Young Sin Roh; Byungman Yoon; Kwon Kyu Yu
Linked Author(s): Byungman Yoon
Keywords: Depth-averaged velocity; Surface velocity; Velocity-dip phenomenon; Velocity profile
Abstract: Laboratory experiments were carried out for various flow and bed conditions, in order to investigate the velocity-dip phenomenon near free surface. Experimental results show that this phenomenon depends mostly on the Froude number rather than bed roughness. Based on the experimental results, a method to estimate the depth-averaged velocity from the measured surface velocity is proposed. The basic idea is to find a log-wake profile which produces the same surface velocity with measured one. Simple application of the log-wake law, however, enevitably underestimates the average velocity. This problem is solved by adding dUs to measured surface velocity. The proposed method was applied to natural streams for verification purpose. Comparison with the average velocities obtained from the accurately-measured velocity profiles reveals that the proposed method estimates the average velocity quite accurately.
Year: 2005