A Vertical2-D Mathematical Model Of Current And Sediment Transport Based On Youngs-VOF Method

Because of the complexity of the three dimensional mathematical model, usually, the research of sediment is simplified according to the topography, the flow characteristics and the nature of the problem. And the2-D vertical sediment model can do quite well in researching the sediment transport where the hydraulic characteristics change little along the lateral while obviously in the vertical direction. Compared to the3-D model, the2-D model requires fewer dates, and is more efficient.In this paper, a2-D vertical model of sediment transport was established by coupling with the time-average Reynolds equations, the k-ε nonlinear turbulence model and the sediment transport model based on the Youngs-VOF method that free surface normal was obtained by ELVIRA method. The turbulent model and suspended sediment transport model were discretized with implicit in the vertical coordinate and explicit in the horizontal coordinate based on the power-law scheme, and bed sand transport model was solved by Euler-WENO scheme. The wall function law and the technique of grid-closing were introduced in dealing with the bottom boundary.Using the established flow model, the1-D shallow water problems having exact solutions, the experiment of solitary wave runup and rundown, and the experiment of steady flow crossing the trench were simulated to analyse the numerical stability, adaptability, shock-capturing property, and the accuracy of the numerical results of the model. On this basis, the experiment of net entrainment from a loose bed, net deposition and evolution of the trench were simulated and analysed by the sediment transport model.The results indicated that the2-D vertical sediment transport model established was effective, and had strong adaptability for nonlinear free surface, could have a good reference for the research of sediment transport driven by the flow with strong discontinuity.