Nonlinear Simulation Of Long Wave Deformation,Fission And Its Interaction With A Vertical Wall

Nonlinear long waves,which are very pervasive in the ocean,can cause serious damages.Their wavelengths range from dozens of meters to several kilometers.Typically,tsunami wave and tidal waves can be seen as nonlinear long waves,causing great loss of life and property.Nonlinear long waves may disintegrate into several small waves after traveling some distance,which can be observed both in tsunami and tidal waves.This disintegration can lead to significant amplification of the wave height and then impact the coastal structures.In the present study,the disintegration of nonlinear long waves over even and un-even bathymetry is investigated numerically.The interaction between a vertical wall and long waves is also investigated.For this purpose,a 2D fully-nonlinear numerical wave flume is developed based on a time-domain higher-order boundary element method.Fully-nonlinear kinematic and dynamic boundary conditions are satisfied on the instantaneous free surface.With this developed model,it is found that the sinusoidal wave generated by the wavemaker can induce higher-order harmonic waves during propagation,which are spatial modulated.The influence on the disintegration by the wavelength and wave height is investigated.Furthermore,the effect of topography on the acceleration of disintegration is also investigated.In the end,we analyze the long wave impact on a vertical wall and the influence of the locations of the wall.In this paper,it is found that long waves deform during its propagation,the degree of which is related to the wavelength of the long wave,and the number of separated waves increases with the increase of incident wavelength and incident amplitude.The reason for this phenomenon is that in the propagation process of long wave,high-order harmonics are generated,and the amplitudes will change periodically in space,and its recurrence distance and amplitude will increase with the increase of wavelength.When multiple high-order harmonic peaks are superimposed,the wave height anomaly increases.In addition,the effect of topography will also accelerate the formation of separated waves,and lead to great wave run-up when it interacts with the structure,causing serious damage.