Numerical Simulation Of Nearshore Sediment Transport In The Process Of Strong Winds And Waves

The problem of sediment suspension, transport and siltation is an important subject of coastal engineering. It is of great benefit to this study to establish the numerical model of describing sediment movement in real situation. Accurate simulation of the wave field and current field under the combined action of wind, wave and current is the basis of effective description and simulation of sediment movement.By this means, the model of irregular wave breaking and energy dissipation fit for mild beach is established firstly. Then the SWAN wave model and the ADCIRC current model are introduced to calculate the wave field and current field, respectively. Through the iteration and coupling calculation of these two models, the wave field and current field interacting with each other are obtained. The computational results are verified by the observed data in site. It is shown that the coupled numerical results are more agreeable with the measured values than the uncoupled results. Based on the carrying capacity formulae of suspended sediment presented by Dou et al., more reasonable formulae for carrying capacity of fine-grained sediments due to combined waves and current, which accord with the evolution of wave energy inside and outside the surf zone, are presented. Based on the coupling simulation of wave field and current field, the sediment transport under the combined action of waves and current during the process of strong winds and waves is simulated using these modified formulae. Thus, a numerical model, which can describe the sediment transport in complicated coastal hydrodynamic conditions, is fully established. The application of the model shows that it reflects the transport principle of fine coastal sediment, i.e. the sediment is mainly suspended by waves and transported by current. The model can be applied to solve the engineering problem of harbor siltation.