Investigation of Ship Motion and Liquid Sloshing Interaction under Wave Conditions

Abstract

This paper investigates internal liquid sloshing within tanks and its impact on ship motion responses. The external ship response is determined using an impulse response function (IRF) method, while the internal flow within the tanks is modelled using the two-phase incompressible Reynolds-averaged Navier-Stokes (RANS) equations. A Volume of Fluid (VOF) technique is employed to capture violent flows, and the Finite Volume Method (FVM) is used for discretization. The viscous flow solver is developed within the open-source CFD framework, Open Field Operation and Manipulation (Open FOAM). A three-dimensional simplified LNG ship with two partially filled tanks in waves is analyzed. Numerical simulations are conducted to examine the coupled effects between ship motion and liquid sloshing, with validation performed accordingly. The results indicate that coupling effects are dominant under low filling conditions. The roll response amplitude operators (RAOs) exhibit a typical anti-rolling effect, where roll motion significantly decreases near ship motion resonance, and double peaks appear at sloshing motion resonant frequencies.