Fully nonlinear numerical investigation on hydroelastic responses of floating elastic plate over variable depth sea-bottom

The time domain fully nonlinear analysis techniques are widely recognized as the unique approach to predict accurate transient behaviors and nonlinear characteristics of the VLFS (very large floating structure). However, these complex issues have not been perfectly solved due to some considerable factors, i.e. wave nonlinearity, displacement nonlinearity, and topography nonuniformity. In this paper, a 2D (two-dimensional) fully nonlinear NWT (numerical wave tank) is developed to investigate the interaction of a monochromatic wave with a floating elastic plate over the variable depth sea-bottom by using the HOBEM (higher order boundary element method). An Euler-Bernoulli-von Karman nonlinear beam model is applied to determine the fluid pressure imposed on the fluid-structure interface. Considering computational cost, the modal functions of a beam with free ends are introduced to approximate the plate displacement. The present model is validated against existing numerical and experimental results for elastic plate placed over flat sea-bottom and wave passing over a submerged object. Numerical calculations are conducted to obtain the hydroelastic higher harmonics and displacement nonlinearity of the elastic finite plate placed over various the trapezoid-shaped sea-bottoms with different shapes and arrangements. The effects of water depths, incident wave amplitudes and incident wave periods on the nonlinear responses of the plate are further emphatically examined.