Influence of Cross-Sectional Shape on Flow Capacity of Open Channels

Abstract

Open-channel flow can be easily found in nature and engineering projects, and the channels’ cross-sections are of various shapes. Research on the flow capacity of open channels with different cross-sections can help deepen our understanding of the dependence of open channels’ general characteristics on cross-sectional shapes at a theoretical level. Furthermore, it has potential practical value in engineering projects. Through theoretical analysis, experimental research, and numerical calculation, two conclusions can be drawn in the present article: (1) A general expression for flow capacity was deduced based on viscous fluid theory, and a parameter describing the influence of cross-sectional shapes on flow capacity, CQ, was obtained. The advantage of our method is that the expression can be used to calculate the parameter directly, which varies with general and flow field characteristics. Another advantage is that the parameter can describe general and flow field characteristics in a uniform way. (2) The width-to-wetted perimeter ratio was selected to describe the cross-sectional shapes. The dependence of the parameter, CQ, on cross-sectional shapes can be summarized as follows: In laminar flow, the parameter depends on the width-to-wetted perimeter ratio only. In turbulent flow at a medium or low Reynolds number, the parameter varied with width-to-wetted perimeter ratio and Reynolds number. In turbulent flow at a high Reynolds number, the parameter was independent of the width-to-wetted perimeter ratio.