PIV Measurements of Side-Cavity Open-Channel Flows --Wando Model in Rivers --

Article type: Research Article

Authors: Nezu, I. | Onitsuka, K.

Affiliations: Department of Civil & Global Environment Engineering, Kyoto University, Yoshidahonmachi, Sakyo-ku, Kyoto 606- 8501, Japan.

Abstract: PIV measurements in side-cavity open-channel flows that simulate "Wando" in rivers, were conducted in a laboratory flume. Five types of side cavities were built by using a transparent plate at the wando flow. The pattern of the instantaneous flow fields was quite different from that of time-averaged ones. It was found that a vortex, which is located in the side cavity, is stable when the junction mouth between the side-cavity and main channel is narrow. In contrast, large-scale unstable vortices are generated semi-periodically when the junction mouth is wide. The free-surface fluctuations in and outside the wando were also measured by three sets of supersonic wave gauges. The amplitude of the water-surface fluctuations is large when the junction mouth is wide as compared with when its mouth is narrow. When the elevation of the free surface in the side-cavity is rising, its elevation in the main channel is falling, and vice versa when the junction mouth is wide.

Keywords: PIV, environmental hydraulics, wando flow, large-scale vortex, free surface

Journal: Journal of Visualization, vol. 5, no. 1, pp. 77-84, 2002