An Experimental Study of Three-Dimensional Separation Surface Sloshing in the Wet Storage Tank of a Floating Offshore Platform

In this work, in order to elucidate the three-dimensional (3D) resonant sloshing dynamics of the oil-water interface in an offshore cylindrical wet storage tank, a series of model experiments are conducted in a completely filled cylindrical tank containing two immiscible liquids. To begin with, a series of free damping tests are performed to experimentally determine the viscous damping rate of the system and to examine the corresponding theoretical solutions. Subsequently, the separation surface wave responses at a series of excitation frequencies including the natural frequencies of first five modes are examined. Finally, the rotary sloshing dynamics at the natural frequencies of the first and second natural modes are systematically explored. Interestingly, it is found that the separation surface rotary sloshing in a two-layer liquid system is much more intricate than one-layer liquid rotary sloshing due to the generation of multitudinous short waves in the long wave. As far as we know, this is the first investigation of 3D separation surface rotary wave motion in a two-layer liquid system without a free surface.