Experimental study on friction velocity and velocity profile of open channel flow

A series of experiments on steady uniform flow in open channel were conducted in a flume.Vertical distributions of flow velocity were measured by using 2-D laser velocimetry.The friction velocities were calculated by three methods based on the experimental data.It is found that:1.the effect of sidewall should be considered when using global resistance method to estimate the friction velocity;2.the log-wake law for describing the velocity profile of open channel flow is better than the logarithmic law and a smaller von Karman constant should be considered when log-law is used to depict the velocity distribution;3.since larger friction velocities are adopted the log-law with adopting a usual von Karman constant( κ =0.4)can be used to express the velocity profile of steady uniform open channel flow.