Dynamic response of a horizontal plate dropping onto nonlinear freak waves using a fluid-structure interaction method

Freak waves are giant surface waves with huge wave heights which can lead to severe slamming to ships and offshore structures. However, few researches have been conducted to investigate the wave impact of a dropping plate against nonlinear freak waves. In order to study this phenomenon and predict the structural response of the dropping plate, a 2-D numerical wave tank is built in which nonlinear freak waves based on the Peregrine breather solution are generated. By combining the fluid domain governed by the Navier-Stokes (N-S) equations and the structure domain discretized by the finite element method (FEM) in a fully-coupled way, the fluid-structure interaction (FSI) is considered. Wave impact of a horizontal plate dropping onto a nonlinear freak wave is simulated and the structural responses of the plate including wetted frequency, maximum deflection, vertical velocity and vibration mode are obtained and analyzed. The unique features of the impact caused by the nonlinear freak wave are revealed through the comparison with a regular-wave-induced impact case. Moreover, the effects of carrier wave amplitude, initial impact location and dropping distance are further investigated and discussed in detail respectively.