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Bright and dark soliton solutions for a new fifth-order nonlinear integrable equation with perturbation terms
*Corresponding author. Tel.: +1 773 298 3397 wazwaz@sxu.edu (Abdul-Majid Wazwaz)
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Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Peer review under responsibility of King Saud University.
Available online 22 August 2011
Abstract
In this paper, we use the solitary wave ansatz method to carry out the integration of a new fifth-order nonlinear equation having perturbation terms. The perturbation terms that are considered are the first-order dispersion term, the power law nonlinearity term, and the fifth- order dispersion term. Both bright and dark soliton solutions are obtained. The physical parameters in the soliton solutions: amplitude, inverse width, and velocity are obtained as functions of the dependent model coefficients. The conditions of the existence of the derived solitons are presented.
Keywords
Bright and dark solitons
K(m, n) equation
Solitary wave ansatz
Introduction
Recent advances in the study of the wave dynamics in nonlinear systems have led to the construction of new integrable models exhibiting a rich variety of exact solutions with interesting properties. A new class of nonlinear partial differential equations (NLPDEs) with constant and variable coefficients that model a lot of physical phenomena has been formulated depending on the physical situation. In parallel, some other NLPDEs are generalized which offer a rich knowledge on the propagation behavior of waves in nonlinear systems of all kinds. Examples of many equations that have been generalized are the K(m, n) equation (Rosenau and Hyman, 1993), the B(m, n) equation (Zhang, 2006; Biswas, 2009b), the ZK(m, n, k) equation (Inc, 2007), the CKG(m, n, k) (Yan, 2007) and so on.
The problem of finding exact solutions for nonlinear models is of great importance, both in mathematical and physical point of view. Based on the exact solutions, we can accurately analyze the properties of the propagating waves in a given nonlinear system. Several kinds of closed form solutions, including compactons, peakons, solitons, cuspons, similaritons, etc., have been obtained under specific conditions. In particular, exact solutions of soliton-type are of general physical interest, because the soliton approach is universal in different fields of modern physics. Notice that the soliton pulses are observed in many physics areas, such as fluid mechanics, plasma physics, optical fibers, hydrodynamics, biology, solid state physics, etc. It is worth noting that, the existence of such shape-preserving waves in the nonlinear systems is the result of exact balance among dispersion (or diffraction) and the nonlinearity effects.
Recently, in the mathematical physics literature has appeared a large amount of new powerful methods to calculate exact solutions to NLPDEs. Among these modern methods of integrability, we can cite the coupled amplitude-phase formalism (Palacios et al., 1999; Du et al., 1995), the hyperbolic tangent method (Malfliet, 1992), Hirota bilinear method (Nakkeeran, 2002; Wazwaz, 2010), the sub-ODE method (Li and Wang, 2007; Triki and Wazwaz, 2009), the solitary wave ansatz method (Biswas and Milovic, 2010; Saha et al., 2009; Triki and Wazwaz, 2009; Biswas, 2008a,b, 2009a) and other methods as well. The solitary wave ansatz has recently been applied successfully to a wide range of NLPDEs (Biswas and Milovic, 2010; Saha et al., 2009; Triki and Wazwaz, 2009; Biswas, 2008a,b, 2009a).
Very recently, Wazwaz (2011a,b) introduced a new fifth-order nonlinear integrable evolution equation in the form
In this work we prove that a family of this new evolution equation having perturbation terms in the form
Here, in (2), a, b, c, α, γ and δ are all constants. The three perturbation terms on the right-hand side of Eq. (2) represent the first-order dispersion term, the power law nonlinearity term, and the fifth-order dispersion term, respectively. Also, noting that the parameter m indicates the power law nonlinearity. On setting a = 1, b = c = 4, and α = γ = δ = 0, Eq. (2) reduces to the model Eq. (1.a).
Bright solitons
In order to obtain the bright soliton solution to (2), the solitary wave ansatz is assumed as (Triki and Wazwaz, 2009; Biswas, 2008a; Biswas, 2009a)
From (3) and (4), we find
From (23) we clearly see that the solitons will exist for
Dark solitons
In this section the search is going to be for the topological 1-soliton solution to the new fifth-order nonlinear evolution equation given by (2). To start off, the hypothesis is given by (Triki and Wazwaz, 2009)
Now from (37) the linearly independent functions are tanhp+j τ for j = ±1, ±3, ±5 and tanh2p+k τ for k = 0, ±2, ±4. Hence setting their respective coefficients to zero yields the following set of equations:
Case 1: p = 1
From (39), this yields
Case 2: p = 2
From (39), this yields
Conclusion
This paper obtains the bright and dark soliton solutions of a new fifth-order nonlinear equation in presence of perturbation terms including the power law nonlinearity. The solitary wave ansatz method is employed to integrate the considered equation. Parametric conditions for the existence of the soliton solutions are found. In view of the analysis, we see that the examined equation is an interesting model for soliton-type solutions. In addition, we note that the solitary wave ansatz method is an efficient method for constructing exact soliton solutions for such nonlinear evolution equation that includes perturbation terms.
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