The moving particle semi-implicit (MPS) method can simulate nonlinear, large-deformation fluid flows, and the discrete element method (DEM) is effective in modeling the interaction of solid bodies. Therefore, it is feasible to simulate the influence of floating foam balls on sloshing by establishing the coupling effect between solid and liquid phases. In this study, the MPS method, with an improved source term and the optimized DEM, is verified by simulations of sloshing and solid-body movements, respectively. The proposed coupling algorithm behaved with acceptable performance in the simulation of the dam break scenario involving multiple layers of solid cylinders. The sloshing numerical tests with floating foams are carried out to demonstrate the accuracy of the MPS-DEM coupling algorithm when the transient behavior is compared.

For the new sandglass-type FPSO, the unique shape of its floating body with oblique side and external expansion can significantly improve the motion performance, but meanwhile may result in specific slamming characteristics in waves. On this basis, this paper establishes a CFD method including numerical wave-tank technique based on the Open FOAM platform. Therein, the velocity-inlet boundary method and the active absorption method are applied for numerical wave-making and wave-absorption. Compared with experimental results, the numerical method can be validated to be accurate enough to simulate wave slamming on floating ocean platforms. Then, the specific slamming phenomena on the sandglass-type floating body under a classic long wave can be investigated by comparing with the cylindrical model, including nonlinear wave rollover and breaking, water cushion, rooster-tail wave, side wave, water tongue, and so on. The mechanism of these phenomena and their effects on slamming pressure are studied. The essences of typical peaks in the time-history curve of the slamming pressure are mainly discussed. More interestingly, the main peak can be found to be related to the small peak due the amount of the broken water and the thickness of the water cushion. Finally, the slamming characteristics of the sandglass-type model in a classic short-wave condition are comparatively discussed.

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.