3D CFD modeling of bed changes at a laboratory channel confluence

The complex three-dimensional flow at river confluence is causing river bed to react with scouring and deposition zones, which in man-made channels can cause problems for navigation, and in natural channels causes lateral movement which might be a threat to riverine structures. Although several studies have studied the sediment pattern of river confluences, a numerical method will be practical in improving the investigation of it in complex zones. In the present study, REEF3D::CFD model, solving the Reynolds-averaged NavierStokes equations with k-ω turbulence model, and sediment transport model is applied to evaluate bed changes in the river confluence. The applicability of this 3D modeling is shown by validating the results with data from laboratory. For the calculation of the free-surface, the model uses the level-set method and 5th-order weighted essentially non-oscillatory discretization scheme. The numerical setup leads to promising results and the representation of the characteristic morphodynamic features at river confluences.