Experimental study of viscous effects on long-duration sloshing characteristics under surge excitations

Abstract

This study aims to investigate the initial transient effects and the final steady-state sloshing characteristics under long-duration surge excitations experimentally. Liquids with different viscosity are applied in the sloshing experiments. The image recognition method is innovatively employed to accurately capture the free surface elevation in these experiments. The viscous effects are found to play a crucial role in altering the damping of the transient mode associated with its natural frequencies and the establishment of the steady-state mode related to the excitation frequency. The mechanism of viscous effects on energy dissipation and transferring is further revealed by Fast Fourier transform and wavelet transform. Then, the damping rates of liquid sloshing with different viscosities are quantitatively measured and analyzed, with reference to the early theories. It is found that with the use of the damping coefficient derived from the experimental data, we are able to describe the long-term evolution of sloshing using the potential flow theory corrected by a damping term, representing the viscous effects of a particular viscous liquid. The accuracy and applicability of this approach is further discussed in this paper.