AN HYDRODYNAMIC MODEL FOR THE CALCULATION OF OIL SPILLS TRAJECTORIES Emilio Ernesto Paladino  emilio@sinmec.ufsc.br Clovis Raimundo Maliska  maliska@sinmec.ufsc.br Computational Fluid Dynamics Laboratory  SINMEC, Mechanical Engineering, Federal University of Santa Catarina, 88040-900  Florianopolis  SC  BRAZIL Phone: +55  48  331-9562 FAX: +55  48  234-1519 Abstract. The aim of this paper is to present a mathematical model and its numerical treatment to forecast oil spills trajectories in the sea. The knowledge of the trajectory followed by an oil slick spilled on the sea is of fundamental importance in the estimation of potential risks for pipeline and tankers route selection, and in combating the pollution using floating barriers, detergents, etc. In order to estimate these slicks trajectories a new model, based on the mass and momentum conservation equations is presented. The model considers the spreading in the regimes when the inertial and viscous forces counterbalance gravity and takes into account the effects of winds and water currents. The inertial forces are considered for the spreading and the displacement of the oil slick, i.e., is considered its effects on the movement of the mass center of the slick. The mass loss caused by oil evaporation is also taken into account. The numerical model is developed in generalized coordinates, making the model easily applicable to complex coastal geographies. Keywords: Environmental Flows - Oil Spill - Numerical Simulation  Generalized Coordinates 1. INTRODUCTION In recent years, the preoccupation with the environment preservation by industries, government authorities and the society in general has increased considerably. This is particularly true in the petroleum branch because of the sea transportation of crude oil by tankers or pipelines because of the significant risk of an accidental spill. The problem is that despite the low frequency of such accidents, the consequences are high. These spills are much more damaging when they occur near shorelines because, besides the environmental impacts, the economical damages ranges from fishing to tourism. The recent oil spill in the Guanabara Bay, Rio de Janeiro, Brazil, caused by a pipeline rupture is a strong example of this broad impact. The detailed knowledge of the spilled oil position and the area covered by the slick is of fundamental importance to take appropriate actions against pollution, like use of floating