Experimental investigation of transient harbor resonance induced by solitary waves

Abstract

Free-surface oscillations within a square harbor subjected to solitary waves are investigated through physical experiments. The effects of various wave heights and water depths on the resonance within the harbor are examined. In this study, the technique of wavelet-based bicoherence spectra is employed for the first time to investigate the nonlinear wave–wave interaction of the transient harbor resonance induced by solitary waves. The results show that the relation between the maximum surface elevation, ηmax, within the harbor and the incident wave height of a solitary wave can be regarded as approximately linear. Moreover, for the same incident solitary wave height, the larger the water depth is, the greater the value of ηmax becomes. The analyses of the wavelet-based bicoherence indicate that the natural modes of the harbor are generated in the following two ways: (1) direct generation from the energy transfer of the solitary waves, and (2) the subsequent generation from the nonlinear interaction between various wave components. The first mechanism plays a decisive role in the generations of low-order natural modes, while the second mechanism also has a vital catalytic role in triggering higher-order modes. Finally, it is examined that the duration of harbor oscillations changes obviously with incident wave heights and water depths.