Teoretical Models Of Suspended Sediment Concentration Distribution Due To Waves

In estuarine and coastal areas, wave is the main dynamic factor for suspension of sediment and plays an important role in nearshore sediment transport. Therefore, it has important significance to study suspended sediment movement due to waves, especially breaking waves in the breaker zone, in studying the mechanism of coastal sediment movement.This paper mainly focuses on the vertical distribution of suspended sediment concentration due to waves. According to the two-dimensional suspended sediment diffusion equation, by analyzing the main factors affecting suspended sediment, the suspended sediment diffusion coefficient models under the non-breaking waves and breaking waves are presented based on the hierarchical model.Nowadays, there are many researches on the distribution of suspended sediment under non-breaking waves. Nevertheless, researches on the sediment suspension due to breaking waves in the breaking zone are relative rare. Because the sand movement in the breaking zone is more difficult to describe and it's influenced by more complex dynamic conditions generated by breaking waves. Therefore, this paper mainly focused on the suspended sediment concentration distribution under breaking waves. In the wave boundary layer, using for reference of eddy viscosity coefficient model which You and Wilkison proposed, give prominence to the turbulent effects on sediment suspended. In the upper water body outside the boundary layer, it is proved that linear distribution should give a better description of the vertical distribution of suspended sediment within the breaker zone, so use a linear distribution, while adding the impact of wave energy dissipation, then the suspended sediment diffusion coefficient is derived. And in the in the transitional water body, taking into account the turbulence shear stress and wave flow velocity distribution under the influence of waves, the suspended sediment diffusion coefficient is given through derivation and simplification. Meanwhile, taking into account the continuity between the layers, the distribution expression of suspended sediment concentration along the depth is established. Finally, comprehensive and reasonable theoretical models of suspended sediment concentration distribution under waves, including non-breaking waves and breaking waves, are both established. The bed form has a significant influence on suspended sediment movement. The bed form characters in the conditions that waves have not been broken as well as have been broken are investigated and the reference concentration in these two conditions are given. The reliability and accuracy of the theoretical model have been improved through these works.The theoretical model is verified by the data for different types of conditions and factors, including different sediments and breaking wave types, and the results obtained from the model agree well with that from experiments. Several factors that may influence the suspended sediment concentration distribution, like bed condition, wave condition, sediment diameter, suspension indicator, temperature , breaking wave types, Correction factor, are analyzed respectively. The changes of the suspended sediment concentration in break zoon are also investigated.