A 3D non-hydrostatic model to predict flow and sediment transport in loose-bed channel bends

The validation and application of a model to solve for the flow, the sediment transport, and bed morphology changes in open channels is discussed. The non-hydrostatic model solves the three-dimensional (3D) incompressible, Reynolds-Averaged Navier-Stokes (RANS) equations in generalized curvilinear coordinates. The model uses adaptive grids in the vertical direction needed to account for changes in the free surface elevation and bed levels due to erosion/deposition at the bed as the code converges toward steady state (equilibrium conditions). The model is used to predict flow and sediment transport through straight and curved open channels, including the 140 degrees open channel bend studied by Olesen (1985) and the 193 degrees very sharp bend studied by Blanckaert (2002). An estimate of the peak non-dimensional shear stress at the banks is deduced function of the ratio between the radius of curvature of the bend and the channel width.