Abstract
Spur dikes are sometimes used to control main flow and they may affect opposite-side flow structures. In this study, effects of spur dike on flow structures in a side concavity zone on opposite side were investigated. The velocity was measured by using PIV method in a laboratory flume. Location of the spur dike relative to concavity zone was changed and its effects were considered. The magnitude of recirculation velocity and water exchange velocity in the concavity zone was enhanced by setting a spur dike on opposite side. This is mainly caused by acceleration of interfacial main flow due to contraction effect of spur dike. This acceleration process is changed with emerged or submerged condition of spur dike. Whereas separation zone behind emerged spur dike is elongated far downstream, that is shortened behind submerged spur dike. Other effects of spur dike such as flow deflection and three-dimensionality also have some effects on water exchange process between concavity zone and main flow.
