Investigation of Interaction Between Oil Spills and Hydrostatic Changes

Abstract

In this paper an assessment of the potential oil outflow from tankers in the case of grounding is presented. The purpose of the study is to investigate how the introduction of double sides, double bottom and damage location will influence the amount of oil escaping from a damaged tank. Furthermore, the objective is to analyze the interaction between oil outflow and hydrostatic changes. In a previous paper, OMAE2008 [1], the pressure integration technique has been utilized to estimate the spill rate and the potential amount of spill without considering the hydrostatic changes. The results were confirmed by CFD simulations. The principles of this technique were presented and its advantages and disadvantages were discussed. In this paper interaction between oil leakage and hydrostatic changes is studied. In order to investigate possible additional oil spill caused by hydrostatic changes two procedures are utilized. In the first procedure, it is assumed that the oil flows out from the cargo tank or water flows in till hydrostatic equilibriums is attained, and subsequently the buoyancy changes due to oil outflow or water inflow are calculated. The additional oil spills caused by the hydrostatic changes are then calculated. The computations are carried out iteratively and continued until the difference between oil loss volumes obtained from two consecutive computations reaches a prescribed tolerance. In reality, there is no time lag between the buoyancy changes and oil loss volume. In order to eliminate the lag, time domain procedure has been applied. In the second procedure, the oil spill and hydrostatic changes are calculated simultaneously in each time step.