Validation of Computational Fluid Dynamics Approach of Lateral Velocity Profile Due to Curvature Effect on Floodplain Levee of Two-stage Meandering Channel

Abstract

Rivers play an integral part in the sustenance of life on earth. The river or natural channel’s sinuous nature causes erosion of its outer wall and silt deposition on its inner wall. These changes in the terrain make it vital to design the meandering compound channel. Levees, both straight and meandering, can be constructed on both sides of the channel to guard the surrounding lands. For doubly meandering levee alignment, the momentum transfer between the main channel and the adjoining floodplains affects the velocity distribution across the channel cross-section. So, hydraulic engineers must investigate this complex flow phenomenon in the case of a doubly meandering compound channel. This study investigates the flow in meandering compound channels using numerical and physical modelling, both of which are important in understanding non-uniform flow and its behaviour. As a result, a research is presented on the sharing of velocity over the cross section of the main channel and the floodplains of meandering compound channels. The geometry of meandering compound channels, having straight as well as sinuous floodplain levees, is chosen for this study. Unlike the experimental models, numerical hydraulic models are remarkably economical. So, in this research, the numerical hydraulic model is adopted to determine the different flow characteristics of compound meandering channels. In this paper, a complete three-dimensional and two-phase Computational Fluid Dynamics (CFD) model of the meandering compound channels is analyzed making use of the RNG K-ɛ turbulence model as well as Volume of Fluid (VOF) methodology. A comparison study between numerical results and experimental results are represented, considering the two different experimental data of compound meandering channel having the main channel meandered with sinuosity (ratio of channel length to the down valley length) of 1.37 and were flanked by straight floodplains as well as meandering floodplains having sinuosity 1.06 on both sides. By error analysis, it is observed that the numerical results agree with that of the experimental ones.