Author(s): A. Tominaga; K. Ijima; Y. Nakano
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Keywords: Submerged spur dike; 3D flow structures; Local flow; PIV
Abstract: To predict and control the sediment transport and the water-quality by using submerged spur dikes, it is necessary to clarify three-dimensional flow structures and instantaneous vortex structures around spur-dike zones. In this study, relative height of the super dike to the water depth is chosen as a design item and its effects on flow structures in spur-dike zones are investigated by using PIV method. Two-dimensional PIV analyses of vertical and horizontal planes reveal the time-averaged flow structures in spur-dike zones with reasonable accuracy. The vertical vortices caused by the top flow and transverse vortices caused by the side flow interact with each other and produce characteristic three-dimensional vortex structures. The vertical profiles of the longitudinal velocity indicate similarity with respect to the crest height of the spur dike. The inverse-flow strength becomes larger at an inner part of the spur-dike zone with an increase of the relative spur-dike height.
Year: 2001