Author(s): Eiji Kojima; Akihiro Kadota; Koichi Suzuki

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Keywords: Submerged and Emerged groynes; PTV analysis; Proper Orthogonal Decomposition (POD); Coherent pattern of vortices and advection

Abstract: River structures beside flow boundaries are called depending on their function such as‘groyne’, ‘spur-dike’, ’Wando’, and so on. These structures are applied to protect channel boundaries from erosion (or scouring) and to maintain sufficient water depth for navigation in periods of low discharge and also to improve the habitat of flora and fauna. A typical Japanese river is characterized by large and sudden variations in discharge due to heavy rainfall. As a result, the groynes are often affected by rapidly varying flows in sub-merged as well as emerged conditions. The present study focuses on the effects of submergence and emergence on the mean and instantaneous-coherent flow structures around a single groyne. Experiments were conducted with a schematized scale model of an existing Japanese groyne by means of the surface flow visualization technique and Particle Tracking Velocimetry (PTV) to analyze the resulting images.

DOI:

Year: 2010