Measurement of Shear Stress and Secondary Flow of the Flows in an Compound Channel

YongHun Tak, DongGyu Jung, Lu Heng, Yong Sung Park, Chang Guen Song, Young Do Kim

Tuesday 30 june 2015

12:33 - 12:36h at Africa (level 0)

Themes: (T) Water engineering, (ST) Experimental facilities and instrumentation, Poster pitches

Parallel session: Poster pitches: 5F. Engineering - Instrument

Nowadays, the accurate measurement of the hydraulic stability of the ecological restoration technology becomes more important as this technology is more and more commonly used in some river restoration projects in Korea recently for both the ecological and environmental functions. The ecological restoration technology should satisfy the hydraulic stability in flood season, but it is not easy to measure its hydraulic stability accurately, especially in complex flows, even though there were already a variety of methods mentioned in many studies. In this study, the shear stress measurement device is used to measure it and shows good results. This device is equipped with a large size pump, an acoustic Doppler velocimetry and an auto movement device, and is mounted on the bottom of a compound channel. The experiment was carried out to measure the bed shear stress and velocity of the flow in the compound channel. Generally, the measurements of the bed shear stress for regular waves can be classified as direct method and indirect method. This paper focuses on direct measurement of the bed shear stress of flows in a compound channel by examining the interaction between the shear plate and shear transducers where the experimental block is moving. At last, the bed shear stress can be calculated based on the displacement caused by the motion of plate which is recorded electronically. The ADV measured the velocity of many testing points in the flow at different heights and lateral positions directly, which can help to identify and analyse the secondary flow.