Abstract

The turbulent structures of flow around the mid-channel braid bar are not adequately investigated so far. Off late, the intrinsic fluvial hydraulics associated with formation of braided rivers interspersed with sand bars are vital topics of research. In this paper, the findings yielded from a research foray on the aforementioned underlying processes are presented. For obtaining the requisite experimental data, the three-dimensional flow velocity components are measured with the help of the Acoustic Doppler Velocimetry (ADV) and these velocity data are analyzed using the quadrant bursting techniques. The flow characteristics are greatly affected by the presence of a mid-channel bar. The depth-averaged contours of turbulent parameters are analyzed in the present study. Herein, the Hole size concept is adopted for separating the bursting events. The effect of Hole size on the quadrant events is also studied. The experiments are performed for different submergence ratios. A new parameter Bursting Index (BI) is proposed in this research to reflect as a quantitative measure of the turbulent bursting effect on the streambed elevation changes. The parameter BI is the ratio of odd events occurrence probability to the even events occurrence probability. The high values of correlation coefficients signifies that the BI is profoundly influenced by the stream bed elevation changes which makes it an ideal parameter for analysing scour and deposition phenomena in real life water management projects. The prime focus on performing the experiments has been to analyze the impact of bar height on the flow structure in the vicinity of the mid-channel bar.

HIGHLIGHTS

  • The new parameter Bursting Index (BI) is proposed in this study to reflect as a quantitative measure of the turbulent bursting effect on the streambed elevation changes observed in the proximity of bar.The high values of correlation coefficients signify that the BI is profoundly influenced by the stream bed elevation changes which makes it an ideal parameter for analyzing scour and deposition phenomena in real life water management projects.

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