Influence of liquid viscosity on surface wave motion in a vertical cylindrical tank

Abstract

In order to explore the influence of liquid viscosity on surface wave motion in offshore cylindrical oil storage tank, hundreds of sloshing experiments were conducted by using four white oils with different viscosities. The present study demonstrates that the excitation frequency and excitation amplitude as well as liquid viscosity have significant influence on sloshing behavior in the cylindrical tank subjected to harmonic horizontal excitation. For low-viscosity oil, when the excitation frequency is very close to or equal to the natural frequency of first asymmetric mode, swirling wave motion with or without breaking can be observed. In addition, it is interesting to note that the sloshing behavior at the second-mode resonant condition is more complicated than that at the first-mode resonant condition, owing to the adjacent asymmetric modes are excited by various nonlinear effects. With the increase of oil viscosity, the surface wave motion becomes more and more stable with smaller wave amplitude and simpler wave pattern. To the best of the author's knowledge, this is the first case of systematic study of sloshing behavior of liquid with different viscosity in the vertical cylindrical tank. The experiments also provide accurate data for the calibration of theoretical and numerical models.