Analysis of flow behavior along the flow depth of a sand bed meandering channel

Flow in a meandering river has complex dynamics and different properties and distributions at each cross-section. So, understanding the three-dimensional flow properties of an actual river requires an adequate amount of time and resources. In this work, an attempt has been made to study the three-dimensional flow properties of a river on a small laboratory scale. Targeting one of the largest peninsular rivers of India, the Mahanadi River, the data sets were collected, and the same Froude number and sinuosity were maintained in the laboratory to perform the experiments. The distribution of three-dimensional flow in a meandering river is an essential aspect to be investigated practically for various river engineering applications. A GIS based morphological analysis were carried out where significant changes of active channel bankline position over the year have been observed and the flow behavior of river responsible for such changes in the pattern has been studied in the current work. In a river, when the flow enters a curve in a meander, the channel’s curvature generates centrifugal force, resulting in a transverse slope on the surface. This interaction between the centrifugal force and transverse pressure gradient induces secondary flows in the cross-sections, which then spread along the bend. As a result, these processes create complex flow properties in all three directions. The detailed experimental study includes graphical illustrations that investigate the 3D flow behavior, which includes profiles of Secondary flow patterns, turbulence intensity profile, turbulent kinetic energy profile, and Reynolds shear stress profile. The objective of this study is to understand the 3D profile distribution of different turbulent parameters at various positions and the effect of curvature and roughness on the three-dimensional flow profiles in the meandering path, which are directly responsible for erosion and accretion at a particular set of channel conditions and under subcritical flow. The study found that the swirling flow only happens in certain parts of the bend and then fades away. At the peak of the bend, the fastest flow is close to the bottom, right where the central and outer parts of the swirling flow meet. Also, this swirling flow helps keep the force on the outer side of the bend low.