Abstract
Weakly nonlinear equations governing the motions of internal waves for two-fluid system are derived using Zakharov's methods. The equations include all of the KdV, B-O and ILW equations, representing the evolution of the whole range of wave-numbers. Spectral methods will be applied directly to the numerical integration of the obtained equations.
Solitary waves with various depth ratis of two-fluids are numerically simulated. As a result, the ILW-solition produces tails in the rear as the depth ratio approaches to 1 and the KdV-soliton steepens its front as the depth ratio approaches to 0.
