Study And Simulation On The Diffusion Of Emulsified Oil In Lakes

With the development of international trade, tour and aquiculture, convenient traffic on water has become more and more important, which result in the increasing of ship number and tonnage. The oiliness sewage discharged has seriously deteriorated water environment. Therefore, it becomes a popular issue of the transfer and transformation of oiliness wastewater in the water.The process that oiliness wastewater into water disappears as time goes on is called water self-purification. The physical and chemical process of oil transformation is named weathering process, which includes evaporation, dissolution, emulsification, dispersion, sedimentation, photo-oxidation and biodegradation. The oiliness wastewater discharged is disturbed by water, and become emulsified oil. Therefore, the transfer and diffusion of emulsified oil is mainly studied in this thesis.In this thesis, a depth-averaged two dimensional unsteady flow equation is developed to describe water flow, and two-dimensional convection-diffusion equation to describe the diffusion of emulsified oil. A two-dimensional water quantity and water quality coupling model using finite volume method (FVM) is established to simulate water flow and the diffusion of emulsified oil. Flux difference splitting (FDS) algorithm, an approximate Riemann solver, is employed to estimate the normal fluxes across the interface of cells. The two-dimension simulation is transferred into solving a series of local one-dimension problem, which is used to simulate the hydrodynamic process and oil pollution diffusion.The model is applied to the simulation of the movement of water flow and the diffusion of oiliness water on Hongze Lake. Different conditions are chosen according to actual situation, and the velocity and acreage of oil diffusion in different conditions is discussed. The result can be used in predicting the diffusion of oiliness wastewater on lake and other large water body. It also provides theoretical base and technical method for the establishment of Oil Spill Emergency Prediction System on shallow lakes and other large water body, and it has built base for further research.