CFD modelling of meandering channel during floods

The three-dimensional Reynolds-averaged Navier–Stokes (RANS) and continuity equations are solved using a standard computational fluid dynamics (CFD) solver to predict flow in a compound meandering channel. High-quality experimental data from the UK Flood Channel Facility (FCF) are used to validate the computational results. The flow velocities, free-surface elevation, bed shear stress and turbulent kinetic energy are predicted reasonably well. The measured and predicted flows are analysed qualitatively and quantitatively to improve further understanding of mean flow, turbulence and secondary flow structures in a compound meandering channel. The streamwise component of the mean vorticity equation is used to quantify the behaviour of secondary flow circulations in terms of their generation, development and decay along the meandering channel. The turbulent kinetic energy equation is used to understand energy expenditure mechanisms of secondary flow circulations. The numerical results show that one of the shear stresses significantly contributes towards the generation of the streamwise vortex and the production rate of turbulent kinetic energy