Development of an integrated model system to simulate transport and fate of oil spills in seas

A three-dimensional integrated model is developed for simulating transport and final fate of oil spills in seas. The model contains two main modules, flow and transport-fate modules. The flow module uses an unstructured finite-volume wave-ocean coupling model. Using unstructured meshes provides great flexibility for modeling the flow in complex geometries of tidal creeks, barriers and islands. In the transport-fate module the oil dispersion is solved using a particle-tracking method. Horizontal diffusion is simulated using random walk techniques in a Monte Carlo framework, whereas the vertical diffusion process is solved on the basis of the Langeven equation. The model simulates the most significant processes that affect the motion of oil particles, such as advection, surface spreading, evaporation, dissolution, emulsification and turbulent diffusion as well as the interaction of the oil particles with the shoreline, sedimentation and the temporal variations of oil viscosity, density and surface tension. The model simulates either continuous or instantaneous oil spills, and also other toxic matter. This model has been applied to simulate the oil spill accident in the Bohai Sea. In comparison with the observations, the numerical results indicate that the model is reasonably accurate.