Author(s): Youichi Yasuda; Ryota Shinozaki

Linked Author(s): Youichi Yasuda

Keywords: No Keywords

Abstract: This study presents the effect of the downstream shape of low drop structures on the velocity field of hydraulic jump. A low drop structure applies if the tailwater Froude number is smaller than 3. Weirs employed for irrigation and drop structures are prone to local scour and river bed degradation even if bed protective blocks are placed to protect the river bed in accordance with hydraulic design manual. This problem may be caused by poor information on the energy dissipator in the tailwater of low drop structure. A river bed control is important to preserve the ecosystem of aquatic animals. The experimental investigation yields that the velocities close to the bottom of a hydraulic jump with low inflow Froude number remain high far downstream. In the experiments, four different downstream shapes (i. e., vertical drop, stepped chute, and two different sloping chutes involving 1/1 and 1/3slopes) were tested. The maximum velocity decays at each section were compared for these four different shapes, resulting in differences for given discharge and drop height. This appears to be caused by the formation of a separation zone at the downstream face of the drop. In turn, no differences were noted on the development of the location of maximum velocity at each section.

DOI:

Year: 2018