Mutual-interaction between bursts and boils very near the free-surface of open-channel flows

In an open-channel flow, a free surface has a large effect on the turbulent energy redistribution near the free surface. When the Froude number increases and the surface-wave fluctuations occur, the damping effect is gradually lost out and the turbulent energy redistribution near the free surface changes largely. It has been pointed out that these characteristics are closely related to the coherent structures. In this study, the damping characteristics are compared between the theoretical model and the experimental data. The effect of the surface-wave fluctuations is then considered by using a function of the Froude number. Furthermore, Reynolds Stress Model (RSM) is used to calculate the turbulent statistics in comparison with the experimental data obtained with a laser Doppler anemometer (LDA). Finally, a relationship between the “bursting phenomenon” generated near the wall and the “surface renewal eddies” near the free surface was evaluated in open-channel flows.