Numerical modeling of deep-water wave breaking

The conventional k-ε model uses constant coefficients which are derived from and verified by quasi-steady turbulent flows. It has been shown that the model can accurately predict the turbulence generation and transport in quasi-steady situations such as broken bores in inner surf zones. During the initial stage of wave breaking process, however, the model overestimates the turbulence level significantly. In this study, a new method is proposed to modify the coefficients in the k-ε model to be functions of the rapid distortion coefficient, which characterizes the turbulence status. The modified model is then used to simulate the breaking wave in deep water. The numerical results are compared with the measurements using the particle image velocimetry (PIV). Excellent agreements are observed for free surface displace and mean velocities and improved agreement is also obtained for turbulence intensity.