抄録
In a prismatic open channel flow, the side-walls create three-dimensional shear stress distribution and then secondary currents are induced by turbulence. This study attempted to make clear three-dimensional turbulent structure in a trapezoidal open channel flow, which was common in actual river, in relating with secondary current structure. Furthermore, the effects of side-wall slope were investigated. As the results, secondary current structure in a trapezoidal channel was changed obviously from that in a rectangular channel. As the side-wall slope became small, new vortex was generated above the side-wall. The free-surface longitudinal vortex was decayed, while bed-wall longitudinal vortex was developed to extend to free-surface. Corresponding with this secondary current structure, primary mean velocity, turbulent structure and the wall shear stress distribution indicated the noticeable patterns paticular to trapezoidal channel.
