越流型水制域内の流れ構造に及ぼす相対水制高の影響

抄録

To predict and control sediment transport and water quality exchange by using submerged spur-dike, it isnecessary to clarify three-dimensional flow structures and instantaneous vortex structures around spur-dikezones. In this study, relative height of super dike to water depth is chosen as a design parameter and its effectson flow structures in spur-dike zones are investigated by using PIV method. Two-dimensional PIV analyses ofvertical and horizontal planes reveal the time-averaged flow structures in spur-dike zones with reasonableaccuracy. The vertical vortices caused by the top flow and transverse vortices caused by the side flow interactwith each other and produce characteristic three-dimensional vortex structures. The vertical profiles of thelongitudinal velocity indicate similarity with respect to the top level of the spur dike. The inverse flow strengthbecomes larger at an inner part of the spur-dike zone with an increase of the relative height