Abstract
Characteristics of inner structure of oblique upward flow in one-sided compound open channel flows at low Reynolds number were investigated by using Particle Tracking Velocimetry (PTV) and flow visualization techniques. The results of flow visualization in the flows with relative deep flood plain depth show that some fixed formative regions of str eamwise vortex exist and that large-scale streamwise vortices developing toward the water surface concentrate over the junction edge of the flood plain. The streamwise vortices have inclined motion toward th e main channel and generate instantaneous secondary flow, local low speed regions and instantaneous Reyno lds shear stress. On the basis of the results, time averaged properties ,which is large-scale twin circular secondary currents including oblique upward flow, are caused by spatial-temporal concentration of streamwi se vortices in the vicinity of the junction edge of the flood plain.
