3D Numerical Simulation Of Tidal Currents And Sediment Using Unstructured Mesh Model

The ocean is a vast treasure trove of resources which is rich in mineral resources, biological resources, water resources, etc. So, it becomes a priority area for the economic and human development, science and technology development. In order to solve the engineering construction, dredging, sedimentation and the port range of issues for the developing of the use of marine, coastal and estuarine areas, we must first understand the hydrodynamic characteristics of project area. Therefore, a more accurate simulation of the hydrodynamic field in the project area is the most important problem. Secondly, we should establish a more reasonable three-dimensional sediment movement and sea-bed transport model for the simulation of the project area. This article uses the three-dimensional hydrodynamic model based on unstructured grid and finite volume method.3D tide and tidal currents in the sea adjacent to Ningbo and Zhoushan is simulated and studied. Latter, the sea-bed sediment transport in the area is made based on the three-dimensional hydrodynamic field.According to the features of Zhejiang coastal tidal, this paper consider the tide site location which has been measured and establish a three-dimensional hydrodynamic mathematical model for the sea adjacent to Ningbo and Zhoushan. In the model, the friction coefficient in the area is calculated using Koutitas Formula. After calculation, the model validation is made by using the velocity flow which was measured in the region. Latter, based on the original suspended sediment movement in FVCOM Model a three-dimensional total sediment mathematical model is established using the Meyer-Peter formula (1948). The model uses the sediment classification of multiple component method in FVCOM which is classified according to the median particle diameter. Suspended sediment was calculated using the diffusion equation and bedload sediment was calculated using the bottom surface sediment movement and change. Using the established three-dimensional hydrodynamic field, the total sediment transport model is applied to the sediment movement and seabed evolution simulation of the sea adjacent to Ningbo and Zhoushan.In addition, an automated program was written in FORTRAN language for the automated numerical simulation of coastal and offshore engineering. The first half part of the program is in order to accomplish the preparatory work of numerical simulation, which consists of treatment of shoreline, location and adding of engineering building, and unstructured mesh generation. The part of numerical simulation was derived from FVCOM model. Later, the codes were modified to become an automated model. After numerical simulation, the program could give the contrast and diversification between no project and project added.Through the comparison of the computed values and the tidal observatories, the numerical results accord well with the measured and the model can be used for3D sediment transport calculation. Through the suspended sediment validation in calculation domain and the bedload sediment change in Jintang waterway, the improved three-dimensional total sediment mathematical model is proved to be reasonable and it can better simulate sediment movement under the action of tide. In a number of examples of new coastal project in coast of Ningbo, this automated program served its purpose of adding new coastal and offshore project and building mathematical model rapidly. The automated program was proved to be feasible and reliable.