If the initial condition for the Korteweg-deVries (KdV) equation is a weakly nonlinear wavepacket, then its evolution is described by the Nonlinear Schrödinger (NLS) equation. This KdV/NLS connection has been known for many years, but its various aspects and implications have been discussed only in asides. In this note, we attempt a more focused and comprehensive discussion including such as is...

We present here the iteration procedure for the determination of free energy ǫ 2-expansion using the theory of KdV-type equations. In our approach we use the conservation laws for KdV-type equations depending explicitly on times t 1 , t 2 ,. .. to find the ǫ 2-expansion of u(x, t 1 , t 2 ,. . .) after the infinite number of shifts of u(x, 0, 0,. . .) ≡ x along t 1 , t 2 ,. .. in recurrent form....

A general class of KdV-type wave equations regularized with a convolution-type nonlocality in space is considered. The differs from the nonlinear nonlocal unidirectional previously studied by addition linear convolution term involving third-order derivative. To solve Cauchy problem we propose semi-discrete numerical method based on uniform spatial discretization, that an extension published wor...

In the past three decades, traveling wave solutions to the Korteweg–de Vries equation have been studied extensively and a large number of theoretical issues concerning the KdV equation have received considerable attention. These wave solutions when they exist can enable us to well understand the mechanism of the complicated physical phenomena and dynamical processes modeled by these nonlinear e...

In a previous paper we proved that long-wavelength solutions of the waterwave problem in the case of zero surface tension split up into two wave packets, one moving to the right and one to the left, where each of these wave packets evolves independently as a solution of a Korteweg-de Vries (KdV) equation. In this paper we examine the effect of surface tension on this scenario. We find that we o...

We discuss a new non-linear PDE, ut + (2uxx/u)ux = uxxx , invariant under scaling of dependent variable and referred to here as SIdV. It is one of the simplest such translation and space-time reflection-symmetric first order advection-dispersion equations. This PDE (with dispersion coefficient unity) was discovered in a genetic programming search for equations sharing the KdV solitary wave solu...

The interaction of solitary waves on shallow water is examined to fourth order. At first order the interaction is governed by the Korteweg–de Vries (KdV) equation, and it is shown that the unidirectional assumption, of right-moving waves only, is incompatible with mass conservation at third order. To resolve this, a mass conserving system of KdV equations, involving both rightand left-moving wa...

In this paper we generalize previous work on the stability of waves for infinite-dimensional Hamiltonian systems to include those cases for which the skew-symmetric operator J is singular. We assume that J restricted to the orthogonal complement of its kernel has a bounded inverse. With this assumption and some further genericity conditions we show that the linear stability of the wave implies ...

The unsmooth boundary will greatly affect motion morphology of a shallow water wave, and a fractal space is introduced to establish a generalized KdV-Burgers equation with fractal derivatives. The semi-inverse method is used to establish a fractal variational formulation of the problem, which provides conservation laws in an energy form in the fractal space and possible solution structures of t...