Solitary-wave solutions of the Degasperis–Procesi equation by means of the homotopy analysis method

The homotopy analysis method (HAM) is applied to the Degasperis–Procesi equation in order to find analytic approximations to the known exact solitary-wave solutions for the solitary peakon wave and the family of solitary smooth-hump waves. It is demonstrated that the approximate solutions agree well with the exact solutions. This provides further evidence that the HAM is a powerful tool for finding excellent approximations to nonlinear solitary waves.     

Exact periodic,cusp, solitary and loop wave solutions of the EX-ROE

The extended reduced Ostrovsky equation (EX-ROE) is investigated by using the dynamical system theory. The bifurcation phase portraits are drawn in different regions of parameter plane. The bounded travelling wave solutions such as periodic waves, periodic cusp waves, solitary waves, peakon, solitary loop waves and periodic loop waves are obtained. The dynamic characters of these solutions are investigated.     

Solitary wave solutions for a generalized KdV–mKdV equation with variable coefficients

In this work, a generalized time-dependent variable coefficients combined KdV–mKdV (Gardner) equation arising in plasma physics and ocean dynamics is studied. By means of three amplitude ansatz that possess modified forms to those proposed by Wazwaz in 2007, we have obtained the bell type solitary waves, kink type solitary waves, and combined type solitary waves solutions for the considered model. Importantly, the results show that there exist combined solitary wave solutions in inhomogeneous KdV-typed systems, after proving their existence in the nonlinear Schrödinger systems. It should be noted that, the characteristics of the obtained solitary wave solutions have been expressed in terms of the time-dependent coefficients. Moreover, we give the formation conditions of the obtained solutions for the considered KdV–mKdV equation with variable coefficients.     

Soliton perturbation theory for a higher order Hirota equation

Solitary wave evolution for a higher order Hirota equation is examined. For the higher order Hirota equation resonance between the solitary waves and linear radiation causes radiation loss. Soliton perturbation theory is used to determine the details of the evolving wave and its tail. An analytical expression for the solitary wave tail is derived and compared to numerical solutions. An excellent comparison between numerical and theoretical solutions is obtained for both right- and left-moving waves. Also, a two-parameter family of higher order asymptotic embedded solitons is identified.     

具强迫项的变系数Burgers方程的特殊孤波结构

利用推广的双曲函数展开法,得到了具强迫项的变系数Burgers方程的几组带有任意函数和任意常数的精确解.根据得到的解,分析了各种可能的孤波结构,发现了运动学特征不同于通常扭结孤立波的特殊扭结孤立波.     

二维空间旋转孤立波的相互作用

利用图形分析方法对(2 1)维频散长波方程的旋转孤立波之间的相互作用进行了详细分析,发现了旋转孤立波相互作用产生的一些新的重要非线性现象.这就是,两个旋转孤立波的碰撞是完全非弹性的,它们碰撞之后可以合并成一个旋转孤立波或一个不旋转孤立波,同时可以发生波形转换及性质改变等现象.这些现象的发现,对非线性水波传播与相互作用规律的进一步认识、对非线性水波的控制与利用都具有重要的理论意义.     

Convergence conditions for iterative methods seeking multi-component solitary waves with prescribed quadratic conserved quantities

We obtain linearized (i.e., non-global) convergence conditions for iterative methods that seek solitary waves with prescribed values of quadratic conserved quantities of multi-component Hamiltonian nonlinear wave equations. These conditions extend the ones found for single-component solitary waves in a recent publication by Yang and the present author. We also show that, and why, these convergence conditions coincide with dynamical stability conditions for ground-state solitary waves.Notably, our analysis applies regardless of whether the number of quadratic conserved quantities, s, equals or is less than the number of equations, S. To illustrate the situation when s < S, we use one of our iterative methods to find ground-state solitary waves in spin-1 Bose-Einstein condensates in a magnetic field (s = 2, S = 3).     

Higher-order split-step Fourier schemes for the generalized nonlinear Schrödinger equation

The generalized nonlinear Schrödinger (GNLS) equation is solved numerically by a split-step Fourier method. The first, second and fourth-order versions of the method are presented. A classical problem concerning the motion of a single solitary wave is used to compare the first, second and fourth-order schemes in terms of the accuracy and the computational cost. This numerical experiment shows that the split-step Fourier method provides highly accurate solutions for the GNLS equation and that the fourth-order scheme is computationally more efficient than the first-order and second-order schemes. Furthermore, two test problems concerning the interaction of two solitary waves and an exact solution that blows up in finite time, respectively, are investigated by using the fourth-order split-step scheme and particular attention is paid to the conserved quantities as an indicator of the accuracy. The question how the present numerical results are related to those obtained in the literature is discussed.     

(2+1)-dimensional ZK–Burgers equation with the generalized beta effect and its exact solitary solution

The (1 ＋1)-dimensional mathematical model had been extensively derived to describe Rossby solitary waves in a line in the past few decades. But as is well known, the (1 ＋1)-dimensional model cannot reflect the generation and evolution of Rossby solitary waves in a plane. In this paper, a (2 ＋1)-dimensional nonlinear Zakharov–Kuznetsov–Burgers equation is derived to describe the evolution of Rossby wave amplitude by using methods of multiple scales and perturbation expansions from the quasi-geostrophic potential vorticity equations with the generalized beta effect. The effects of the generalized beta and dissipation are presented by the Zakharov–Kuznetsov–Burgers equation. We also obtain the new solitary solution of the Zakharov–Kuznetsov equation when the dissipation is absent with the help of the Bernoulli equation, which is different from the common classical solitary solution. Based on the solution, the features of the variable coefficient are discussed by geometric figures Meanwhile, the approximate solitary solution of Zakharov–Kuznetsov–Burgers equation is given by using the homotopy perturbation method. And the amplitude of solitary waves changing with time is depicted by figures. Undoubtedly, these solitary solutions will extend previous results and better help to explain the feature of Rossby solitary waves.     

Energy transfer in a dispersion-managed Korteweg-de Vries system

We consider the propagation of weakly nonlinear, weakly dispersive waves in an inhomogeneous media within the framework of the variable-coefficient Korteweg-de Vries equation. An analytical formula with which to compute the energy transfer between neighboring solitary waves is derived. The resulting expression shows that the energy change in a variable KdV system is essentially due the two-wave mixing, contrary to the energy change in a nonlinear Schrödinger system, which results from the intrachannel four-wave mixing. By considering the case of Gaussian solitary wave solutions, we have determined the transfer of energy in the system analytically and numerically.     

The Exp-function approach to the Schwarzian Korteweg–de Vries equation

By means of the Exp-function method and its generalization, we report further exact traveling wave solutions, in a concise form, to the Schwarzian Korteweg–de Vries equation which admits physical significance in applications. Not only solitary and periodic waves but also rational solutions are observed.     

A linearized implicit finite-difference method for solving the equal width wave equation

A linearized implicit finite-difference method is presented to find numerical solutions of the equal width wave equation. The method has been used successfully to investigate the motion of a single solitary wave, the development of the interaction of two solitary waves and an undular bore. The obtained results are compared with other numerical results in the literature. A stability analysis of the scheme is also investigated.     

Solitary wave simulations of Complex Modified Korteweg-de Vries Equation using differential quadrature method

Complex Modified Korteweg-deVries Equation is solved numerically using differential quadrature method based on cosine expansion. Three test problems, motion of single solitary wave, interaction of solitary waves and wave generation, are simulated. The accuracy of the method is measured via the discrete root mean square error norm L₂, maximum error norm L_∞ for the motion of single solitary wave since it has an analytical solution. A rate of convergency analysis for motion of single solitary wave containing both real and imaginary parts is also given. Lowest three conserved quantities are computed for all test problems. A comparison with some earlier works is given.     

New compacton soliton solutions and solitary patterns solutions of nonlinearly dispersive Boussinesq equations

The special exact solutions of nonlinearly dispersive Boussinesq equations (called B(m,n) equations), u_tt−u_xx−a(uⁿ)_xx+b(u^m)_xxxx=0, is investigated by using four direct ansatze. As a result, abundant new compactons: solitons with the absence of infinite wings, solitary patterns solutions having infinite slopes or cups, solitary waves and singular periodic wave solutions of these two equations are obtained. The variant is extended to include linear dispersion to support compactons and solitary patterns in the linearly dispersive Boussinesq equations with m=1. Moreover, another new compacton solution of the special case, B(2,2) equation, is also found.     

Solitary Wave Benchmarks in Magma Dynamics

We present a model problem for benchmarking codes that investigate magma migration in the Earth’s interior. This system retains the essential features of more sophisticated models, yet has the advantage of possessing solitary wave solutions. The existence of such exact solutions to the nonlinear problem make it an excellent benchmark problem for combinations of solver algorithms. In this work, we explore a novel algorithm for computing high quality approximations of the solitary waves in 1-, 2- and 3 dimensions and use them to benchmark a semi-Lagrangian Crank-Nicolson scheme for a finite element discretization of the time dependent problem.     

The new exact solitary and multi-soliton solutions for the (2+1)-dimensional Zakharov–Kuznetsov equation

In this paper, by employing two different simplest equation methods, the (2$+$1)-dimensional Zakharov–Kuznetsov (ZK) equation derived for describing weakly nonlinear ion-acoustic waves in the plasma is investigated. With the aid of the Bernoulli equation and the coupled Burgers’ equations, the electric field potential of ZK equation are formally obtained, which are presented as the new solitary and multi-soliton solutions. Meanwhile, the electric field and magnetic field can be accordingly obtained. In addition, the significant features of the variable coefficient and parameter are discovered. The results show that the solitary and multi-soliton solutions are precisely obtained and the efficiency of the methods is demonstrated. These new exact solutions will extend previous results and help to explain the features of nonlinear ion-acoustic waves in the plasma.     

A numerical study of k(3,2) equation

The Korteweg-de Vries (Kdv) equation has been generalized by Rosenau and Hyman [7] to a class of partial differential equations (PDEs) which has solitary wave solution with compact support. These solitary wave solutions are called compactons

Compactons are solitary waves with the remarkable soliton property, that after colliding with other compactons, they reemerge with the same coherent shape. These particle like waves exhibit elastic collision that are similar to the soliton interaction associated with completely integrable systems. The point where two compactons collide are marked by a creation of low amplitude compacton-anticompacton pair. These equations have only a finite number of local conservation laws

In this paper, an implicit finite difference method and a finite element method have been developed to solve the K(3,2) equation. Accuracy and stability of the methods have been studied. The analytical solution and the conserved quantities are used to assess the accuracy of the suggested methods. The umerical results have shown that this compacton exhibits true soliton behavior.     

A finite difference method for korteweg-de vries like equation with nonlinear dispersion

The Korteweg-de Vries (KdV) equation has been generalized by Rosenau and Hyman [3] to a class of partial differential equations (PDEs) which has solitary wave solution with compact support. These solitary wave solutions are called compactons. Compactons are solitary waves with the remarkable soliton property, that after colliding with other compactons, they reemerge with the same coherent shape. These particle like waves exhibit elastic collision that are similar to the soliton interaction associated with completely integrable systems. The point where two compactons collide are marked by a creation of low amplitude compacton-anticompacton pair. These equations have only a finite number of local consevation laws. In this paper, an implicit numerical method has been developed to solve the K(2,3) equation. Accuracy and stability of the method have been studied. The analytical solution and the conserved quantities are used to assess the accuracy of the suggested method. The numerical results have shown that this compacton exhibits true soliton behavior.

     

Exact travelling wave solutions for a diffusion-convection equation in two and three spatial dimensions

The modified extended tanh-function method were applied to the general class of nonlinear diffusion-convection equations where the concentration-dependent diffusivity, D(u), was taken to be a constant while the concentration-dependent hydraulic conductivity, K(u) were taken to be in a power law. The obtained solutions include rational-type, triangular-type, singular-type, and solitary wave solutions. In fact, the profile of the obtained solitary wave solutions resemble the characteristics of a shock-wave like structure for an arbitrary m (where m>1 is the power of the nonlinear convection term).     

Two-stage continuation algorithms for Bloch waves of Bose-Einstein condensates in optical lattices

Bloch waves of Bose-Einstein condensates (BEC) in optical lattices are extremum nonlinear eigenstates which satisfy the time-independent Gross-Pitaevskii equation (GPE). We describe an efficient Taylor predictor-Newton corrector continuation algorithm for tracing solution curves of parameter-dependent problems. Based on this algorithm, a novel two-stage continuation algorithm is developed for computing Bloch waves of 1D and 2D Bose-Einstein condensates (BEC) in optical lattices. We split the complex wave function into the sum of its real and imaginary parts. The original GPE becomes a couple of two nonlinear eigenvalue problems defined in the real domain with periodic boundary conditions. At the first stage we use the chemical potential μ as the continuation parameter. The Bloch wavenumber k(kx,ky), and the coefficient of the cubic term are treated as the second and third continuation parameters, respectively. Then we compute the Bloch bands/surfaces for the 1D/2D problem with linear counterparts. At the second stage we use μ and k/kx or ky as the continuation parameters simultaneously with two constraint conditions. The states without linear counterparts in the GPE can be obtained via states with linear counterparts. Numerical results are reported for both 1D and 2D problems.