Numerical Simulation And 3D Visualization Of Oil Spill At Sea

Ocean covering approximately 71%of Earth's surface.In recent years,with the rapid development of the global economy,world seaborne has increased which makes it has an important role in international transportation.Increased seaborne also increased the risk of oil spill pollution at sea.Oil spill incident leads to negative impacts on the marine environment,ecosystem,and wildlife at sea.Therefore,making a timely and prompt response decision is extremely important and necessary.Carrying out a real offshore oil spill exercise is costly,risky and environmentally damaging.It is necessary to construct a three-dimension oil spill numerical model to simulate and predict all the characteristics of the oil spill at sea.The three-dimension visualization in real-time oil spill simulation will give an overview of an oil spill incident and strengthen the emergency human sources training and drilling.On the other hand,it can minimize costs and reduce harm compared to real drills.At present,many oil spill model is a two-dimension model and still not satisfied a fluid simulation model too.My thesis mainly resolves an instantaneous oil spill with spreading and drifting processes and constructs a hydrodynamic tidal model of the Bohai Sea,and the main research content as below:1.Construct and calculate the hydrodynamic tidal model of the Bohai Sea by Mike 21 Flow Model and Mike Zero software which is based on the ADI method.The speed and direction of current at a certain point are determined by using the linear interpolation of base vector values on the triangular mesh based on the Leendertse principle,and then it is used for calculating for all the areas of Bohai Sea.The result of the calculation will be compared with the observation data to assess the effect of the method.2.Based on the geometry method to simulate the trajectory of oil slick moving under the effect of wind and current.The model uses the empirical study of Lehr to calculate the spreading area and spreading speed which is based on Fay's model.The drifting and diffusion model is based on the Hoult' model.3.When the maximum area was reached,I will apply the Poisson Disk algorithm to render oil slick into particles,in contrast,we go back to the calculate oil position again.Oil particles were moving and diffusion under the effect of the wave,wind,and current,all are rendered in one platform namely Unity3D which makes a nice canvas of oil spill simulator.4.After the oil particle model is constructed by Poisson Disk Sampling,a realistic fluid model is needed to build.Therefore,based on the oil particles' three-dimensional information of every time,we need to construct the function of the shape of the oil slick and render the oil slick surface.All points on this surface have the same function value,known as the iso-surface.The metaball method determines the overall surface by precisely calculating each corner's function value in every voxel according to particles around,so it can be used to construct the function of iso-surface based on the oil particle model.After the iso-surface function is determined,the Marching Cube method is represented to construct iso-surface in the three-dimension regular data field.5.When the oil slick surface was constructed,it is only a raw data of oil characteristic,Unity Shader was used to rendering oil slick in a realistic and vivid.The light,normal was calculated by the surface shader,vertex shader,and fragment shader to render light,the reflection,refraction,caustic of the oil film.In my dissertation,the author used the Poisson Disk Sampling algorithm to generate oil particles of different sizes,and Marching Cube algorithm to reconstruct the iso-surface so that the oil film is in irregular shape and can be randomly dispersed into small parts.Then the 3D visualization effect of the oil spill at sea is presented in a good result.