New Drag Force Formula of Bending Stems in Deriving Analytical Solutions of Velocity Profile for Flow Through Flexible Vegetation

Investigations of water flow movements affected by vegetation is a research hotspot in vegetation ecological restoration. The theory and equations of the flow velocity distribution under the influence of rigid vegetation are relatively mature. This study proposes a new drag force equation that varies with the vegetation bending angle and a new analytical solution of the velocity profile. Comparisons between the model calculation and experimental data, results showed that this new proposed model produced accurate simulations for flow through flexible vegetation for various deflections. In addition, this analytical model was verified to be applicable to rigid vegetation without a bending angle. Moreover, the features of the parameters adopted in this analytical equation are discussed, and the empirical equation for these parameters are presented. This study further improves the research in the field of environmental fluid mechanics and can serve as a theoretical underpinning for the ecological restoration of river courses. Key Points A new drag force equation of flexible vegetation is proposed based on the bending angle This new drag force equation of bending vegetation can recover to the traditional equation when applied to erect rigid vegetation New analytical solutions of velocity profiles for flexible and rigid vegetation are established