Experimental Study of Flow Characteristics in Real-Scale Meandering River Channel

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Dongsu Kim, Geunsoo Son

Wednesday 1 july 2015

12:00 - 12:15h at Oceania (level 0)

Themes: (T) Sediment management and morphodynamics, (ST) River morphodynamics

Parallel session: 9B. Sediment - River

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Flow characteristics in the meandering river channel has been well studied in terms of experimental and numerical perspective. However, most of experimental studies to figure out flow and turbulent characteristics in meandering channel has been conducted on the small-scale of laboratory experiment. Few field experiments have been conducted because of the lack of proper in-situ instruments to capture three-dimensional flow and no flow controllable site. This study applied the recent advancement of acoustic instruments as well as real-scale meandering river channel to find out the mechanics of flow in various meandering conditions in bigger scale. ADCPs were applied to derive secondary flow in the successive cross-sections and validated them in conjunction with field ADV measurements. In particular, the longitudinal pattern of maximum velocity and depth along the bend were investigated to look inside the details of the flow variation driven by meandering of channel. Structure of longitudinal velocity profiles revealed that the flow profiles alters along the location in the bend and mostly did not follow conventional velocity law such as log-law. Turbulent flow and bed shear stress distribution in conjunction with scouring process in the meandered channel were scrutinized in terms of their interaction. The development of secondary current and its strength caused by meandering showed that they are much more complicated than the results from laboratory experiments. Overall, the hydrodynamic and morphologic process in the meandering channel in this study indicated that they are substantially different from those from the small-scale laboratory experiments.