複断面蛇行開水路流れの水理特性について(2)

Abstract

Flow structure in meandering channels during floods is strongly distorted and has a 3-dimensional nature. This nature is brought by the interaction process between the upper and lower layer flows.Many parameters, both geometrically and hydraulically, have influences on determining this process. Thus it is important to explore in a wide range the effects of these parameters on the structure of compound meandering flow.This paper shows some experimental results of velocity and turbulence measurements in compound meandering channels. Particular care was taken to examine the effects of sinuosity (s) and cross-sectional shape of the main channel. Their roles as determinants for the flow structure identified through the examination are as follows:1) Sinuosity strongly influences the interaction process due to the change of the crossing angle between the upper and lower layer flows. However the structural alteration due to this angle change can only be seen within a rather limited area in the crossover region.2) The channel cross-sectional shape also has significant effect on the flow structure, specially on the structure near the side wall of the channel. From the viewpoint of channel conveyance, its effect on the flow exchange process between the main channel and the flood plain is of particular importance.