aTokyo Nonlinear Analysis Research Center, Musashi Institute of Technology, Tamazutsumi, Setagaya, Tokyo 158 8557, Japan
Abstract:
In this paper, we derive the governing equations of the envelope created by nearly bichromatic waves defined as the waves with wavenumber spectrum has two closely approaching peaks and spreads over around two peaks. The obtained governing equation has higher-order terms related to the distinctive quantities of nearly bichromatic waves. We show a nonlinear Schrödinger type equation governs the envelope created by nearly bichromatic waves, up to third order, under some conditions.