Author : Amgoth Ashok 1
Date of Publication :22nd February 2018
Abstract: In this study, scaling of dominant Reynolds shear stress within the vegetation patch is performed. To simulate such flows, an emergent and sparse vegetation patch is prepared using acrylic cylindrical rods with regular spacing in streamwise and lateral directions. The vegetation patch is placed in the middle cross-section of the open channel flume. Three-dimensional flow velocities interior of the vegetation patch are measured using a Nortek Vectrinoplus Acoustic Doppler Velocimeter. The measurements are taken along the centerline in the vegetation patch. The dominant Reynolds shear stress (RSS) interior of the vegetation patch is found to be less than the vegetation-free fully developed flow. In addition, RSS values are decreasing in the downstream direction within the vegetation patch although there is a similarity in the shape of RSS profiles. The decrease in flow rate in the downstream direction along the centerline is responsible for the decrease in RSS values. There found to be a bandwidth in which all RSS values near the bed are contained. In the similarity analysis, the RSS profiles scaled such that non-dimensional RSS profiles collapse on each other. The similarity of non-dimensional RSS profiles is attempted in the paper. Scaling demonstrates wake effect, velocity defect, disturbance in the boundary layer and etc.in addition to highlighting the typical behaviour of RSS profiles in any general emergent vegetation flows.
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