ABSTRACT

Wind-induced water-waves in free-surface flows such as actual rivers and artificial channels, promote the transport of a large amount of oxygen and heat through the interface between water and wind layers. The wind supplies the water with momentum and turbulent kinetic energy, and thus, there exist significant effects of wind-induced waves on open-channel turbulence. It is inferred that the near-bed region is also influenced by these interfacial fluctuations in shallow open-channel flows. In pure smooth open-channel flows, turbulent boundary layers are developed both beneath the air-water interface and over the bottom, and coherent motions of ejections/sweeps are observed, as pointed out by previous studies. It is very important to reveal such a wall turbulence structure which is strongly related to the transport of suspended sediment and dissolved nutrients. However, there are a lot of uncertainties about the wind effects on wall turbulence structure. So, the present study focuses on these challenging topics.