Study On The Forecast Models For Oil Spills In Seas Based On Lagrange Tracking

Marine oil spill accidents have occurred frequently, causes people to the widespread concern of oil spills at sea and a considerable amount of research, in order to reduce oil spill incidents on the marine environment impact, studying on the behaviors and fate of the oil spill forecast model on the marine appears to be particularly important. Offshore oil usually used the oil pipeline transport or tanker transport, there are two great risks. In view of this, based on the research work of former summarized and the need of the research task, the systemic review is made of the model for hydrodynamics and oil spills. Then, the N-S equation and turbulent diffusion theory as the main theory, the Lagrangian tracking and Lagrangian integral method as the main numerical calculation method, namely the establishment of a subbed pipeline oil spill prediction model and transport and transformation of two-dimensional, three-dimensional oil spill mathematical model at sea. The main contents include:Two higher-order splitting schemes, SOWMAC and Crank-Nicolson FEM have been applied to three-dimensional advection-diffusion equation based on the idea of the operators splitting method. The third scheme proposed in this paper is based on the classical ADI scheme and the accuracy of the advection term of it can reach the spatial fourth-order, while classical ADI scheme only can reach the spatial second-order. Finally, two typical numerical experiments show that the solutions of these three schemes compare well with that given by the analytical solution and other traditional scheme.For subbed pipeline oil spill accidents, a subbed pipeline oil spill model to simulate the increase, spread, dissolution and emulsification process of underwater oil spill has been established. Using Lagrangian integral technology, that is, every moment of the oil spill along the path as a center of the control unit, the oil spill into account not only the physical convection-diffusion process, but also its chemical change, such as dissolution and emulsification action. In addition, the model also took into account the role because of the shear caused by convection and entrainment process, and the numerical simulation results and experimental results are compared.Princeton Ocean Model (POM) and unstructured finite volume mode (FVCOM) have been used to simulate the current of the Dalian Bay, Bohai Sea and HKT bay, Japan, and the numerical simulation results are validated.For oil spill accidents caused by oil tanker, models for the two-dimensional and three-dimensional oil spills to simulate the behavior and fate have been established. Based on the "oil particle" idea, Lagrangian tracking simulation of the oil spill off transportation, diffusion and transformation, in this method, the oil film can be a lot of small oil droplets, oil droplets provide for each change over time of the coordinates. Each time, first of all, oil droplets with both local and fluctuating velocity and flow rate movement, said that with the amount of turbulent fluctuation theory of random diffusion coefficient, and then consider the evaporation oil droplets, dissolution, emulsification, the settlement and attachment to the shore. Considered the above process and based on wind, current, both isotropic and anisotropic diffusion formula has been applied to 2D oil spill model and comparing their simulation results. The vertical turbulent diffusion and horizontal movement of the second Stokes induced net transport has been considered in the 3D oil spill model which is based on wind, current and wave. 2D and 3D oil spill model have been applied to simulation the oil spill accident occurred in June 1990 in the Bohai Strait under the wind, tide and wave action and computation the transportation, diffusion and transformation process, and with the observed values were compared.