Abstract
During the transportation and storage of liquefied natural gas (LNG), sloshing in partially filled cargo tanks poses significant risks to structural integrity and operational safety. Conventional anti-sloshing devices, such as internal baffles, are incompatible with membrane-type tanks due to strict requirements on internal geometry and material integrity. To address this challenge, this study proposes an eccentric foam floater (EFF), which enhances energy dissipation through controlled mass asymmetry without modifying the tank’s internal configuration. Building upon the buoyant-ball concept, the EFF introduces an offset between geometric center and center of mass, thereby promoting additional rotational motion, inter-floater and floater–wall friction, and fluid–structure interaction effects. Model experimental investigations using a six-degree-of-freedom motion platform, combined with discrete element method (DEM) simulations, demonstrate that the EFF consistently outperforms its homogeneous counterpart in suppressing sloshing-induced pressure fluctuations across a broad range of excitation conditions. The results highlight the potential of mass eccentricity as a design principle for passive, structure-preserving sloshing mitigation in membrane LNG tanks.