Investigating the Combined Effect of Tall and Short Vegetation Patches in Open Channel Flow

Abstract

Double-layered vegetation patches in open channels have a significant effect on flow structures. While several investigations have been conducted on double-layered vegetation, none have specifically addressed the impact of submergence levels. This study employs a Reynolds stress turbulence model to examine rigid, discontinuous double-layered submerged vegetation patches. For simulations and post-processing, ANSYS (FLUENT) utilizing Computational Fluid Dynamics (CFD) techniques was used to analyze the differences in mean stream velocity within the model domain. Various distributions and profiles of mean stream and depth-averaged velocities are presented in this study. It was observed that the velocity decreases noticeably in the gap region, as the flow stabilizes there. Additionally, fluctuations in mean stream velocity were noted directly behind both the smaller and taller vegetation dowels. Notably, distinct velocity transition zones consistently detected at the tops of the vegetation dowels. Experimental vegetation patches should be installed along riverbanks, wetlands, or in storm water channels to monitor their effects on flow velocity.