Analysis of Hydraulic Jump and Energy Dissipation in Flow Through Emergent Vegetation Under Varying Froude Numbers

Abstract

Emergent vegetation in an open channel is a significant factor in flow resistance and has greater influence on flow characteristics. This paper aims to compare the significance of emergent vegetation under various flow conditions including sub and supercritical flow conditions. The methodology utilizes two types of flow condition (sub and supercritical flow), and each type was further considered on the basis of varying discharge and constant channel bed slope and vice versa. For example, under subcritical flow Froude number was defined as a (Fr_(CD-VS) represent Froude number under constant discharge and varying channel bed slope) and (Fr_(CS-VD) represent Froude number under constant channel bed slope and varying discharge). A similar flow condition was defined under supercritical flow conditions. Various parameters such as backwater rise, hydraulic jump, energy reduction, fluid force (RFI%) and moment index reduction (RMI%) as well as reduction of overflow volume (∆Q%) were investigated. The result has been explained in two phases such as sub and supercritical flow. Under sub-critical flow, an undulated hydraulic jump was observed on the downstream side of the vegetation and a maximum energy reduction was 28% in the case of (Fr_(CS-VD)) and 33.4% in the case (Fr_(CD-VS)). Moreover, in the case of (Fr_(CS-VD)) the maximum value of the RFI% and RMI% increased by increasing the values of (Fr_(CS-VD)). The maximum reduction of overflow volume observed was 72% in the case of (Fr_(CS-VD)). Under supercritical flow, an undulated hydraulic jump was observed on the upstream side of vegetation and energy reduction increases by increasing the values of (Fr_(CS-VD)). The maximum value of the RFI% and RMI% observed was 16.67% in the case of (Fr_(CS-VD)). These results contribute to understanding the complex interactions between vegetation and flow dynamics, with implications for managing and mitigating flood risks in vegetated environments.