Optimization of Vegetated Open Channel for Enhancing Flood Resilience: Numerical Analysis

Abstract

Vegetated open channel significantly altered the dynamics of floodwater. For this purpose, the current research aims to optimize a vegetated open channel by altering bed roughness for enhancing flood resilience. This paper utilized an ANSYS-Fluent-based computational fluid dynamics (CFD) under diverse flow conditions. The roughness conditions of the channel bed were altered from 0 to 14.32mm under different flow conditions. The result of the numerical model was validated against an experimental study conducted in a controlled laboratory setting. The result demonstrated a close alignment between experimental and numerical models with coefficient of determination (R2) and root mean square error (RMSE) values of 0.96 and 0.0176, respectively. After validating the result of numerical models, further cases were simulated in ANSYS Fluent to observe flow dynamics under diverse flow conditions. Parameters like velocity distribution and turbulent kinetic energy (TKE) were determined. The results indicate that stream-wise depth average velocity and TKE increased 47.3% and 66.4% by varying Froude number (Fr) from 0.40 to 0.65. However, upon introducing bed roughness in a vegetated open channel, it was observed that the stream-wise depth average velocity and TKE reduced by 3.4% and 4.17% under roughness conditions of 7.22mm. By increasing the roughness conditions of the channel bed, the velocity distribution and TKE were further reduced. Therefore, the result of this study concluded that increasing vegetated open channel bed roughness enhanced flow energy dissipation, reduced erosive forces, stabilized channels, and provided an effective nature-based framework for enhancing flood resilience.