Numerical Simulation Of Oil Spill Spreading Drift And Source Backward Tracking

Inland river navigation is an important part of comprehensive transportation system and comprehensive utilization of water resources.Inland river navigation plays an important role in promoting regional economic development,optimizing industrial layout and serving opening policy.Inland river navigation has the advantages of high efficiency,low cost and low energy consumption,which can not be replaced by other transportation modes.Inland river navigation has become an important mode of transportation.With the rapid development of national economy,the inland river transport market is unprecedentedly prosperous.The development of inland river navigation increases the risk of oil spill pollution.The Yangtze River waterway is an important waterway for goods and materials transportation in China.In the fluctuating backwater area of the Three Gorges Reservoir area,the number of dangerous chemical vessels and oil tankers increases with the increase of the number of dangerous chemical ports and wharves.The increase of the number of ships leads to the increase of hidden dangers of water traffic safety.The risk of oil spill pollution is more prominent due to various marine accidents.Oil spill pollution poses a great threat to human life,material property and ecological environment.Therefore,after the accident,it is of great significance to predict the drift and diffusion characteristics of oil spill scientifically,find the pollution source in time and take emergency measures.Numerical simulation of oil spill is a hot topic in this field.Most of the existing researches are focused on the ocean and estuary areas,while the researches on the long and narrow inland channels are relatively limited.In this paper,the typical reach of the Three Gorges Reservoir area is taken as the research area.Two-dimensional flow mathematical model,oil spill spread and drift mathematical model and oil spill source backward tracking mathematical model are established by using FORTRAN language.The establishment of the model provides an important theoretical basis for the prevention and simulation of oil spill pollution in the Three Gorges Reservoir area.The model provides strong technical support for the establishment of risk assessment and decision management system for sudden oil spill accidents in rivers.The specific research content is as follow:(1)First of all,two-dimensional flow mathematical model is established.The basic equations of two-dimensional flow mathematical model,the method of solving the equations,the boundary conditions and their processing methods,and the generation of coordinate grid are introduced.Based on the measured data of Luoqi reach of the Yangtze River,the water level,velocity distribution and buoy flow direction of the two-dimensional mathematical model are verified.Verification ensures the simulation accuracy of the model.The establishment of two-dimensional mathematical model provides the flow field basis for the oil spill model.(2)Based on the oil particle model,oil spill spread and drift mathematical model is established.The behavior and destination of oil spill is embedded in the framework of oil spill pollution mathematical model.The best partition time,the best partition quantity and the size of oil particles are determined.The velocity values of the two-dimensional flow grid are interpolated to each oil particle.The model was calibrated and verified by using the basic data of oil spill hydrodynamic test in generalized flume.Finally,a mathematical model of oil spill spread and drift is established,which can effectively reflect complex flow conditions and the composition of different riparian boundaries.The model is used to predict the diffusion and drift trajectory of oil spill in water,and to simulate the change of spilled oil diffusion shape.(3)Based on oil spill spread and drift mathematical model,oil spill source backward tracking mathematical model is established.By changing the oil spill model,the reverse operation of oil spill spread and drift prediction program is realized.According to the observed oil pollution situation in a specific location,the possible source of oil spill is inversed,the drift path of oil spill is inversed,and the location of oil spill pollution source is determined.Finally,a oil spill source backward tracking mathematical model suitable for the characteristics of inland waterway is constructed,which can comprehensively reflect the complex river morphology and flow conditions.(4)Oil spill spread and drift model and oil spill source backward tracking model are applied to the actual engineering river reach.The Fengjie reach in the perennial backwater area and the Luoqi reach in the fluctuating backwater area of the Three Gorges Reservoir area are selected to carry out the numerical simulation of oil spill spread and drift and source backward tracking.The pollution process of oil spill under typical operation conditions and different oil spill combinations of the Three Gorges reservoir is obtained.The numerical simulation results of oil spill spread and drift model and oil spill source backward tracking model are analyzed to verify the feasibility and applicability of the model.