Turbulent Hydrodynamics Along Lateral Direction in and Around Emergent and Sparse Vegetated Open-Channel Flow

Abstract

Jute plantation is one of the important crops in India and Bangladesh region. The vegetation density of Jute plantations is usually sparse. No comprehensive experimental study has been carried out till date to investigate turbulent characteristics in the lateral direction at interior and exterior of sparse and emergent vegetation patch. The proposed study investigates important turbulent characteristics at different cross sections at upstream, interior and downstream of emergent and sparsely vegetated open-channel flow. An array of seventy uniform rigid acrylic cylindrical rods with regular spacing was used to represent the emergent sparse vegetation patch. Three-dimensional instantaneous velocities were measured by a Nortek VectrinoPlus ADV. From this study, it was evident that time-averaged streamwise velocities were decreasing in interior of the vegetation along the streamwise direction. Inside the vegetation patch, time-averaged lateral velocities were directed towards the nearest sidewall. Time-averaged vertical velocities were negative throughout the cross section at upstream of the vegetation patch. But absolute magnitudes are decreasing in interior and downstream of the vegetation patch. Turbulent kinetic energy was decreasing inside the vegetation patch, and the peak values were located far from the channel bed in interior and downstream cross sections through the vegetation.