Turbulent Flow Characteristics in Interior and Wake Region of Emergent and Sparse Vegetation Patch

Abstract

Vegetation in the flow field affects flow hydrodynamics. For example, emergent vegetation patch in the flow field produces changes in river morphology, changes in flow velocity and turbulence. Therefore, investigation of flow characteristics in and around the emergent vegetation patch is a topic of importance. The main aim of this study is to investigate the self-similarity and scaling of profiles of streamwise and lateral velocities, turbulence intensities, Reynolds shear stress and kinetic energy in the interior and the wake region of the vegetation patch. A Nortek Vectrinoplus Acoustic Doppler Velocimeter (ADV) was used to measure the point velocity data throughout the depth along the centerline of the vegetation patch in the streamwise direction. Seventy numbers of acrylic cylinders were used to make the emergent vegetation array in the middle of a laboratory flume. In this study, flows with two different Reynolds numbers and two different aspect ratios were investigated. The results demonstrate self-similarity of streamwise velocity profiles normalized by depth averaged velocity in the outer region in the interior and wake region of the emergent and sparse vegetation patch irrespective of Reynolds number and aspect ratio of flow. Similarly, wall wake similarity was observed in the Reynolds shear stress distribution.