Internal solitary waves propagating from deep water to shallow water in a two-layer fluid are numerically simulated by solving the set of nonlinear equations in consideration of both strong nonlinearity and strong dispersion of waves. As an internal solitary wave travels from deep water to shallow water, almost all its wave energy is transmitted from the deep- to the shallow-water regions. A BO soliton propagates into a shallow-water region, generating KdV solitons, the characteristics of which depend on the positional relationship between the interface and the critical level. In the case where the static interface is below the critical level in a shallow-water region, disintegration of an internal solitary wave occurs remarkably, after which the available potential energy of the wave train becomes larger than its kinetic energy.
