Numerical Study on Resistance to Flow in Meandering Channels

Abstract

Focusing on the effect of the meandering planform, two functions are investigated by a numerical experiment: the first represents the ratio between the intensities of the resisting forces acting on a meandering flow and its corresponding straight flow; and the second represents the ratio between the intensities of the resisted meandering flow itself and its corresponding straight flow. Both functions depend on the sinuosity (or relative curvature) and the width-to-depth ratio. The two functions and their numerical results are thoroughly analyzed, showing the following: (1) meandering causes an increase in the resistance to flow, with a greater resistance occurring in the stream having an “intermediate” sinuosity (or “large” relative curvature) and a “small” width-to-depth ratio; (2) there is an imbalance between the driving and resisting forces in a meandering stream, and the degree of this imbalance has a direct interrelation with the intensity of the “kinetic-energy-weighted” convergence of flow; and (3) the ratio of kinetic to potential energy of a meandering flow cannot be reflected by the square of the (Chézy) resistance factor alone, and the two things manifest different variation patterns versus the sinuosity and the width-to-depth ratio. These findings are likely to advance the understanding of the resistance to flow in meandering channels.