Freak wave in a two-dimensional directional wavefield with bottom topography change. Part II. Oblique incident waves and crossing waves

This study investigates the oblique incident wave and the wave crossing in nonlinear wave evolution under variable directional spreading and bathymetry. Building on the depth-modified nonlinear Schrödinger (dNLS) model for a two-dimensional random wavefield, we incorporate wave refraction and symmetric crossing wave systems to numerically simulate realistic ocean conditions more accurately. Monte Carlo simulations are conducted to analyse wave spectrum, surface morphology and statistical moments (skewness and kurtosis). Results show that small incident angles have a very limited effect on extreme events and nonlinear interactions in a single system, but even small-angle wave crossing leads to an increase in the occurrence probability of freak waves from single system to multi-system. As the crossing angle increases, the enhanced dispersion suppresses transverse wave groupiness and reduces the likelihood of extreme events.