【作者】 汪守东；

【导师】 沈永明；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2008， 博士

【摘要】 海上溢油事故的频繁发生,引起了人们对海上溢油的普遍关注和大量研究,为了减小溢油事故对海洋环境造成的影响,对海上溢油行为和归宿预报模型的研究就显得尤为重要。海上石油通常使用海底石油管线或油轮运输,两者均存在很大风险。鉴于此,本文根据前人研究工作的总结和本课题研究的需要,对近海水动力和溢油模型进行了系统的文献综述。在此基础上,以N-S方程和紊流扩散为主要理论、以Lagrange追踪法和Lagrange积分法为主要求解方法,分别建立了海底管线溢油预报模型和二维、三维海面溢油迁移转化预报模型,研究的主要内容包括:在算子分裂法的基础上,将SOWMAC和Crank-Nicolson有限元两种高精度分裂格式推广应用于污染物三维对流扩散方程,同时对经典ADI格式的对流项做了改进,改进后的格式的对流项对空间具有四阶精度,而经典ADI格式对空间只有二阶精度,并对两种典型的浓度场进行了数值模拟,且将这三种高精度格式的计算结果与解析解以及其它传统差分格式的计算结果进行了对比。针对海底管线溢油事故,建立了海底管线溢油预报模型以模拟分析水下溢油的上升和扩散过程。模型采用Lagrange积分法,不仅考虑了溢油的对流扩散过程,还考虑其化学转化过程,如溶解和乳化。此外,模型还考虑了由于剪力和对流作用引起的卷吸过程,且将数值模拟结果与实验值进行了对比。水动力学模型分别使用普林斯顿海洋模式(POM)和非结构有限体积模式(FVCOM),对大连湾、渤海和日本博多湾的潮流场进行了数值模拟,并对模拟结果进行了验证。针对油轮溢油事故,建立了二维和三维海面溢油行为和归宿预报模型。模型基于“油粒子”概念,采用Lagrange追踪法模拟海面溢油的迁移、扩散和转化。在此方法中,油膜可用大量的小油滴表示,对每个油滴都规定随时间而变化的坐标系。在每个时间段,首先油滴随当地的时均流速和脉动流速而移动,表示紊动脉动的分量同随机理论得到的扩散系数有关,然后再考虑其挥发、溶解、乳化、沉降和附着在岸边等过程。二维溢油模型基于的环境动力有风场和潮流场,使用了各向同性和各向异性两种紊动扩散公式,并对两种公式的模拟结果进行了比较。在三维溢油模型中增加了油滴的垂向紊动扩散和水平运动的二阶Stokes波导净输移,其基于的环境动力有风场、潮流场和波浪。模拟分析了在风、潮流和波浪作用下发生在1990年6月渤海海峡溢油事故中油膜的迁移、扩散和转化过程,并将模拟结果与观测值进行了对比。更多还原

【Abstract】 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.更多还原