NUMERICAL INVESTIGATION OF BREAKING IRREGULAR WAVES OVER A SUBMERGED BAR WITH CFD

The study of breaking irregular waves is of great practical interest, because of the waves found in the nature. Regular waves are seldom found in the field. Irregular waves can be viewed as the superposition of a number of regular waves (wave components) with the different frequencies and the amplitudes. The breaking process for irregular waves is more complex as compared to breaking regular waves. The energy transfer between the individual wave components of different frequencies also takes place during the breaking process. Due to this, the spectral characteristics of the incident wave spectrum change during the breaking process. The main purpose of the study is to investigate the hydrodynamics during the interaction of breaking irregular waves with a submerged bar.

A NUMERICAL STUDY OF FREAK WAVE GENERATION IN RANDOM SEAS OVER A SUBMERGED BAR

Freak waves, also called rogue waves and giant waves, are much larger and steeper than the surrounding waves, can cause severe accidents, and can be formed in both coastal and offshore regions. The past researchers on freak waves in coastal regions are mainly focused on the statistical properties, and the generation mechanism of such large waves are not yet discussed intensively. The aim of the present study is to examine the generation process of freak waves in unidirectional propagating random waves over a submerged bar using a fully nonlinear numerical wave model, SWASH. It was found that freak waves are readily formed at the seaward part of the crest of the bar and gradually emerged from an intense wave group. The enhancement of the bound higher harmonics in the shoaling process is the main reason to form such large waves in shallow water. On the crest bar of the bathymetry, the extreme wave gradually vanished, mainly due to the releasing of bound higher-harmonics to free wave components.