Numerical Study on Nonlinear Energy Transfer of Gravity Wave Spectra in Finite Water Depths

Abstract

The characteristics of nonlinear energy transfer of gravity wave spectra have been investigated through theoretical, experimental and numerical approaches so far. However, most of them were for deep water waves, and very few were for finite water waves. In this paper, we numerically investigated the characteristics of nonlinear energy transfer in finite water depths by the FD-RIAM method (Hashimoto, et.al 1996, Komatsu, et.al, 2001) having high accuracy and stability. The amplification factor of nonlinear energy transfer and frequency downshift were investigated as functions of some parameters, such as relative water depth and energy concentration parameters in frequency and direction, etc. The drawback of the amplification factors used in DIA were also discussed with comparing the results computed by FD-RIAM.