Lateral velocity distribution in open channels with partially flexible submerged vegetation

Abstract

This study implemented three analytical models to investigate the lateral distribution of depth-averaged streamwise velocity in a rectangular channel with lateral, unevenly-distributed, flexible submerged vegetation. Secondary flow, vegetation drag, and turbulent shear were introduced into the momentum equations to represent the interaction between vegetation and flow. Comparison of model results and experimental data indicated that predictions were improved with a mixing layer model, which considers the secondary flow term in the mixing region, particularly for channels with a high aspect ratio. The research established a relationship between the vegetation drag coefficient and the Reynolds number. A sensitivity analysis of the dimensionless eddy viscosity coefficient and bed friction factor indicated that the coefficient had as significant an impact as the second factor on the lateral velocity profile. A reasonable dimensionless eddy viscosity coefficient is essential to predict velocity accurately.