Analysis of dynamic heeling moment due to liquid sloshing in partly filled ships tanks for realistic range of rolling periods - a case study

Liquid sloshing phenomenon is a result of partly filled tank motions. As a tank moves, it supplies energy to induce and sustain a fluid motion. Both the liquid motion and its effects are called sloshing. The interaction between ship’s tank structure and water sloshing inside the tank consists in the constant transmission of energy. As the ship rolls, the walls of a partly filled tank induce the movement of water. Liquid sloshing phenomenon occurring in partly filled ships tanks directly affects the stability of the vessel. However, only static calculations are carried out onboard ships nowadays and static transfer of liquid weight is taken into account in the course of routine stability calculation and assessment. Since previous researches reveal the necessity of dynamic approach towards liquid movement onboard ships, the investigation is focused on problems related to time dependent wave-type phenomena. This aspect is omitted in the course of standard ship stability calculations. The set of numerical simulations of liquid sloshing taking place in moving tanks is carried out. Among many obtained characteristics, the heeling moment due to sloshing is emphasized and thoroughly investigated. The realistic range of possible metacentric heights and rolling periods is examined. The influence of ship’s rolling period on the heeling moment due to liquid sloshing is analyzed for one exemplary seagoing vessel as a case study. However, the conclusions can be generalized to some degree and comprise many other ships.