Analysis of Drag Forces Contribution for Oil Ship Behavior

Vessel´s behavior can be studied using numerical modeling in order to minimize oil ship accidents. This study includes results from a ship simulation with external forces. The bi-dimensional numerical model was written in FORTRAN 95 language, considering three degrees of freedom. Two hydrodynamic drag were used to test the model. Drag forces were tested in two vessels with considerable physical differences. In the beginning of the simulation the distinct drag forces did not promote influence in the standard speed of the ships. It happens due to the bigger influence of initial forces associate with vessel deceleration. The variations of the ship´s speed for the different drag formulations show more variation when the vessel is influenced by the thrust and the pressure gradients associated to the relative movement of the ship and the waves. Thus, the results suggest that the drag associated with the effect of the wave field generated around the hull of the ship has less influence on the vessel´s trajectory than the drag due to ship´s friction with the environment.