Numerical simulation of sea-wave diffraction with random phases on breakwaters

Abstract

Introduction. Numerical simulation of sea gravity waves interaction with seaport barriers using modern numerical wave models is considered. The predictive power of some commonly used models is examined in relation to the diffraction of sea waves with a random phase in comparison with known analytical methods and experimental data. Materials and methods. Numerical simulation is carried out using modern numerical wave models implemented in the DHI MIKE 21 software package. A spectral wave model with a function for correcting wave diffraction in shallow water and a phase-resolving wave model based on the Boussinesq equations are used. Results. Distribution of diffraction coefficients behind the breakwaters of the conventional port water area has been obtained for all models. As a result of the comparison, it was found that models of irregular waves (waves with random phases) have better wave energy distribution behind the breakwaters as compared to regular (monochromatic) wave models. It is noted that the type of frequency distribution of random waves has almost no effect on the diffraction coefficients of the water area, while the angular distribution, on the contrary, has a significant effect. Conclusions. The wave model based on the Boussinesq equations in the irregular wave approximation is determined as the numerical wave model with the best predictive ability. The spectral wave model with diffraction correction function, which is less demanding on computer power, also made it possible to obtain results close to the reference ones. It is confirmed that regular wave propagation modelling of sea waves can give incorrect results in those seaport water areas where wave diffraction effects are strong.