Author(s): K. Morota; M. Tsuchiya
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Keywords: Seigyu groins; Drag force coefficient; Roughness coefficient; Turbulence intensity; Reynolds stress
Abstract: The objective of this study is to clarify the effects of spur dikes on a stream by means of a hydraulic model experiment. In the experiment, Seigyu groins were set at the confluence of a river and at a curve. In addition, for comparison training jetties and cross dikes were set up in the river channel. We studied hydraulic characteristics on the basis of the results. The results show that a Seigyu, like a training jetty, divides flow into two at a confluence, and shifts the core of flow at a curve. A Seigyu can control a stream, but lowers discharge capacity because placement of a Seigyu or cross dike narrows cross sectional area. Consequently, water level upstream rises. Drag coefficient CD, an index of resistance characteristics of a Seigyu groin, amounts to nearly 1, the same as for a cylinder. Roughness coefficient n is 1.1 or 1.25 times that found when Seigyu groins are not provided. Further, analysis of turbulent flow revealed instantaneous and minute streams in around Seigyu groins.
Year: 2003