Surface Gravity Waves with Strong Frequency Modulation

J. Ocean Eng. Technol. 2006;20(3):1-6.

Lee Kwi-Joo;Shugan Igor V.;An Jung-Sun;

Department of Naval Architecture & Ocean Engineering, Chosun University;Department of Naval Architecture & Ocean Engineering, Chosun University;Department of Naval Architecture & Ocean Engineering, Chosun University;

Keywords: Surface gravity waves, Phase kinks, Negative frequence, Crest pairing, Waves modulation

Abstract

Modulation theory describes propagation of surface waves with deep wave number and frequency modulation. Locally spectrally narrow wave packet can have accumulated large scale frequency shift of carrier wave during propagation. Some important nonlinear modulation effects, such as negative frequencies, phase kinks, crest pairing, etc., often observed experimentally at long fetch propagation of finite amplitude surface wave trains, are reproduced by the proposed theory. The presented model permits also to analyze the appropriately short surface wave packets and modulation periods. Solutions show the wave phase kinks to arise on areas' of relatively small free surface displacement in complete accordance with the experiments.