Numerical Simulation of Sloshing of Water in Ship Tanks During Sequential Ballast Water Exchange in Seaways

In recent years, ballast water has been blamed for a variety of marine pollution problems, particularly for transporting harmful aquatic organisms from one part of the world to another and damaging the ecosystem of the new areas. A relatively simple mechanism to control this problem is to exchange ballast water on the high seas between ports in order to remove invasive species before the ship reaches its destination. However, some issues regarding ballast exchange on the open sea need to be addressed before this operation is introduced. One of them is the sloshing of the sea water in the ballast tank. In this paper, ballast water exchange on the open sea by means of the Sequential exchange method is simulated. Irregular seaways are generated from the ISSC spectrum, and the sloshing response of the water in the ballast tanks of a large merchant ship is numerically computed by using a finite difference code developed by the authors. The results showed that there is little possibility that severe sloshing presents a serious problem in regard to the ballast tank’s strength, especially in the case of a bulk carrier whose tanks are generally short in length, with sloshing anticipated only at the low water level.