Abstract: In the present study, the coupled level set and volume of fluid (CLSVOF) interface capturing method is employed to investigate the three-layer liquid sloshing in a rectangular wash tank installed aboard floating production storage and offloading (FPSO). The study shows that in the case of multi-layer liquid sloshing, the relevant physics can be much more complicated compared with the single liquid sloshing case. When the forced oscillation frequency is slightly away from the resonant frequency, there is an interesting phenomenon that the internal sloshing between liquid-liquid interfaces is significantly more pronounced than the actual oscillation of the top free surface. Another important issue for multi-interface problems is Kelvin-Helmholtz instability along the interface. Finally, the excellent capability of the CLSVOF method for multi-layer liquid sloshing simulation is validated by the qualitative comparisons of numerical and test results.

Key words: rectangular tank; three-layer liquid; sloshing; coupled level set and volume of fluid (CLSVOF) method; Kelvin-Helmholtz instability