EFFECTS OF RELATIVE SUBMERGENCE ON COHERENT TURBULENCE STRUCTURE IN VEGETATED OPEN-CHANNEL FLOW

Abstract

It is necessary in river environment and hydraulic engineering to investigate the hydrodynamic properties in vegetated canopy rivers, in which velocity distributions are largely changed in the vertical direction. In particular, the relative submergence, i. e., the ratio of the water depth H to the vegetation height h, influences velocity profiles significantly. For example, in high submergence, we can see an outer layer in which a logarithmic layer is formed. Whereas, in low submergence, the flow is directly influenced by the vegetation elements. So, in this study, turbulence measurements were conducted intensively in vegetated open-channel flows by changing the relative submergence, and consequently, mean-flow properties, turbulence structure and coherent motions were revealed and discussed in detail.