Hindawi Publishing Corporation Abstract and Applied Analysis Volume 2013, Article ID 284865, 7 pages http://dx.doi.org/10.1155/2013/284865 Research Article Abundant Exact Solition-Like Solutions to the Generalized Bretherton Equation with Arbitrary Constants Xiuqing Yu, Fengsheng Xu, and Lihua Zhang Department of Mathematics Sciences, Dezhou University, Dezhou 253023, China Correspondence should be addressed to Xiuqing Yu; sddzyxq@163.com Received 20 January 2013; Accepted 26 February 2013 Academic Editor: Abdel-Maksoud A. Soliman Copyright © 2013 Xiuqing Yu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Riccati equation is employed to construct exact travelling wave solutions to the generalized Bretherton equation. Taking full advantage of the Riccati equation which has more new solutions, abundant new multiple solition-like solutions are obtained for the generalized Bretherton equation. 1. Introduction Nonlinear partial differential equations (PDE) are widely chosen to describe complex phenomena in physics sciences. Searching for exact solutions to nonlinear differential equations plays more and more important role in nonlinear science. Recently, various direct methods have been proposed, such as the tanh-function method [1, 2], the Jacobi elliptic function expansion method [3, 4], the F-expansion [5–8], sine-cosine method [9, 10], and the homogeneous balance method [11–13]. Among them, the tanh-function method is improved continuously [14–17] as one of the most effectively straightforward methods for constructing exact solutions to PDEs. In the paper an extended tanh-function method is used to solve the generalized Bretherton equation with arbitrary constants. In [18], Bretherton introduced the partial differential equation π’π‘π‘ + π’π₯π₯ + π’π₯π₯π₯π₯ + π’ − π’2 = 0 (1a) in time and one spatial dimension as a model of a dispersive wave system to study the resonant nonlinear interaction between three liner models. The modified Bretherton equation π’π‘π‘ + π’π₯π₯ + π’π₯π₯π₯π₯ + π’ − π’3 = 0 (1b) was studied by Kudryashov [19], Kudryashov et al. [20], and Berloff and Howard [21], and its travelling wave solutions were obtained. Our aim in this paper is to investigate multiple solitonlike solutions to the generalized Bretherton equation in [22] by using the solutions to the Riccati equation: π’π‘π‘ + πΌπ’π₯π₯ + π½π’π₯π₯π₯π₯ + πΏπ’ + πΎπ’3 = 0. (1c) 2. Multiple Soliton-Like Solutions to the Generalized Bretherton Equation We assume the travelling wave variable π’ (π₯, π‘) = π’ (π) , π = π₯ − ππ‘, (2) where π is the speed of the travelling wave. Making use of the travelling wave transformation (2), (1c) is converted into an ordinary differential equation (ODE) for π’ = π’(π) as follows: (π2 + πΌ) π’σΈ σΈ + π½π’(4) + πΏπ’ + πΎπ’3 = 0. (3) We assume that the solutions to (3) can be expressed in the form π π’ (π) = ∑ ππ ππ , π = −π (4) 2 Abstract and Applied Analysis + 14π½π−2 πΆ2 π΅2 + 6πΎπ2 π0 π−2 + 6πΎπ1 π−1 π0 where π is a solution of the Riccati equation, πσΈ = π΄ + π΅π + πΆπ2 , (5) where ππ (π = 0, ±1, ±2, . . . , ±π) π΄, π΅, and πΆ are constants to be determined later, and either π−π or ππ can be zero, but they cannot be zero together. Substituting (4) into (3) together with (5) and considering the homogeneous balance between the highest-order derivative π’(4) and the nonlinear term π’3 , we obtain π = 2. Thus the solution to (3) takes the following form: π’ (π) = π2 π2 + π1 π + π0 + π−1 π−1 + π−2 π−2 . (6) Substituting (6) with (5) into (3) and collecting all the terms of the same power of π, the left-hand side of (3) is converted into another polynomial of π. Setting the coefficients of ππ (π = 0, ±1, ±2) to zero yields a set of algebraic equations 3 − 120π½π−2 π΄4 = 0, πΎπ−2 + 8π½πΌ1 πΆπ΅π΄2 + πΎπ03 = 0, 6πΎπ2 π−1 π0 + πΌπ−1 π΅2 + 6π2 π2 π΅π΄ + π1 π2 π΅2 + 3πΎπ1 π02 + 2π1 π2 πΆπ΄ + 2πΌπ1 πΆπ΄ + 3πΎπ12 π−1 + πΏπ1 + 6πΌπ2 π΅π΄ + 22π½π1 πΆπ΅2 π΄ + 30π½π2 π΅3 π΄ + 16π½π1 πΆ2 π΄2 + π½π1 π΅4 + 6πΎπ2 π1 π−2 + 120π½π2 πΆπ΅π΄2 = 0, 4πΌπ2 π΅2 + 8πΌπ2 πΆπ΄ + 136π½π2 πΆ2 π΄2 + 16π½π2 π΅4 + 3πΎπ2 π02 + πΏπ2 + 3π2 π΅πΆ + 3πΌπ1 πΆπ΅ + 15π½π1 πΆπ΅3 + 4π2 π2 π΅2 + 60π½π1 π΄π΅πΆ2 + 8π2 π2 πΆπ΄ + 3πΎπ12 π0 + 23π½π2 πΆπ΅2 π΄ + 3πΎπ22 π−2 + 6πΎπ2 π1 π−1 = 0, 2 3πΎπ−1 π−2 + 24π½π−1 π΄4 + 96π½π−2 π΅π΄3 = 0, 40π½π1 πΆ3 π΄ + 2πΌπ1 πΆ2 + 50π½π1 πΆ2 π΅2 + 10πΌπ2 πΆπ΅ 2 330π½π−2 π΅2 π΄2 + 60π½π−1 π΅π΄3 + 3πΎπ−1 π−2 + 6πΌπ−2 π΄2 2 + 3πΎπ0 π−2 + 6π2 π−2 π΄2 = 0, + 6πΎπ2 π1 π0 + πΎπ13 + 10π2 π2 π΅πΆ + 3πΎπ22 π−1 + 130π½π2 πΆπ΅3 + 440π½π2 πΆ2 π΅π΄ 2 40π½π−1 π΄3 πΆ + 3πΎπ1 π−2 + 2π2 π−1 π΄2 + 10π2 π−2 π΅π΄ + 2πΌπ−1 π΄2 3 + 50π½π−1 π΅2 π΄2 + 6πΎπ−1 π0 π−2 + 130π½π΅3 π΄ + πΎπ−1 + 2π1 π2 πΆ2 = 0, 3πΎπ22 π0 + 3πΎπ12 π2 + 6π2 π2 πΆ2 + 60π½π1 πΆ3 π΅ + 440π½π−2 πΆπ΅π΄2 + 10πΌπ−2 π΅π΄ = 0, + 240π½π2 πΆ3 π΄ + 330π½π2 πΆ2 π΅2 + 6πΌπ2 πΆ2 = 0, 2 6πΎπ1 π−1 π−2 + 60π½π−1 π΄2 πΆπ΅ + 3πΎπ2 π−2 + πΏπ−2 3πΎπ22 π1 + 24π½π1 πΆ4 + 336π½π2 πΆ3 π΅ = 0, 2 + 3πΎπ−1 π0 + 3πΌπ−1 π΅π΄ + 8π2 π−2 πΆπ΄ πΎπ23 + 120π½π2 πΆ4 = 0. (7) + 8πΌπ−2 πΆπ΄ + 136π½π−2 πΆ2 π΄2 + 3πΎπ02 π−2 + 4πΌπ−2 π΅2 + 4π2 π−2 π΅2 + 16π½π−2 π΅4 Solving (7) with the help of the symbolic computation software Maple, we obtain the following. + 3π2 π−1 π΅π΄ + 15π½π−1 π΅3 π΄ + 232π½π−2 πΆπ΅2 π΄ = 0, Case 1. One has 16π½π−1 π΄2 πΆ2 + 6π2 π−2 πΆπ΅ + 2πΌπ−1 π΄πΆ + π½π−1 π΅4 π−1 = 0, + πΏπ−1 + 6πΎπ2 π−1 π−2 + 30π½π−2 πΆπ΅3 + 3πΎπ−1 π02 π1 = 2π΅πΆ√ + 2π2 π−1 π΄πΆ + 6πΎπ1 π0 π−2 + πΌπ−1 π΅2 + 120π½π−2 πΆ2 π΄π΅ + 6πΌπ−2 πΆπ΅ + 22π½π−1 π΄πΆπ΅2 −30π½ , πΎ Case 2. One has 2 + 3πΎπ2 π−1 + 8π½π−1 π΄πΆ2 π΅ + πΏπ0 + π1 π2 π΅π΄ π−1 = 0, + π2 π−1 π΅πΆ + πΌπ1 π΅π΄ + πΌπ−1 π΅πΆ + 16π½π2 πΆπ΄3 2 π0 = 2π΄πΆ√ −30π½ , πΎ πΏ = 4π½ (−8πΆπ΄π΅2 + π΅4 + 16π΄2 πΆ2 ) . 2πΌπ−2 πΆ2 + 2πΌπ2 π΄2 + 2π2 π2 π΄2 + 2π−2 πΆ2 + 3πΎπ12 π−2 2 −30π½ , πΎ π2 = 2πΆ2 √ π = ±√−πΌ − 5π΅2 π½ + 20πΆπ΄π½, 2 + π−1 π2 π΅2 + 3πΎπ1 π−1 = 0, 3 π−2 = 0, 3 3 + π½π1 π΅ π΄ + 14π½π2 π΅ π΄ + 16π½π−2 πΆ π΄ + π½π−1 π΅ πΆ π−2 = 0, π1 = −2π΅πΆ√ −30π½ , πΎ π2 = −2πΆ2 √ π0 = −2π΄πΆ√ −30π½ , πΎ −30π½ , πΎ (8a) Abstract and Applied Analysis 3 π = ±√−πΌ − 5π΅2 π½ + 20πΆπ΄π½, πΏ = 4π½ (−8πΆπ΄π΅2 + π΅4 + 16π΄2 πΆ2 ) , (8b) where π΄, π΅, and πΆ are arbitrary constants, but πΆ cannot be zero. Case 3. One has π−1 = 0, π2 = 0, π−2 = 2π΄2 √ π1 = 0, 30π½ π0 = 2π΄πΆ√ , πΎ πΏ = −16π½π΄ πΆ . Case 4. One has π2 = 0, π0 = − −15π½ (coth (π₯ + π√−πΌ − 5π½π‘) 2πΎ 2 ± csch (π₯ + π√−πΌ − 5π½π‘)) − π√ 2 (8c) π−1 = 0, π’1π = π√ π−2 = 2π΄2 √ π1 = 0, 30π½ −15 ± √165 πΆπ΄√ , 15 πΎ 30π½ , πΎ 2 − π√ π’1π = π√ 2 + π√ Case 5. One has π1 = 0, 30π½ π0 = −2π΄πΆ√ , πΎ π−2 30π½ = −2π΄ √ , πΎ 2 π’1π = π√ 2 π΅ = 0, + π√ Case 6. One has π2 = 0, π0 = π1 = 0, (−15 ± √165) πΆπ΄ 15 π−2 = −2π΄2 √ 30π½ √ , πΎ −15π½ , 2πΎ −15π½ (csc (π₯ + π√−πΌ + 5π½π‘) 2πΎ (8e) π−1 = 0, (9c) − cot (π₯ + π√−πΌ + 5π½π‘)) πΏ = −16π΅π΄2 πΆ2 . π = ±√−πΌ − 60πΆπ΄π½, −15π½ , 2πΎ ± sec (π₯ + π√−πΌ + 5π½π‘)) (8d) where π΄, π΅, and πΆ are arbitrary constants, but π΄ cannot be zero. 30π½ , πΎ π’1π = π√ π = π√−πΌ + (−30 ± 2√165) πΆπ΄π½, πΏ = −4π΄2 πΆ2 π½ (13 ± √165) , (9d) −15π½ , 2πΎ tan (π₯ + π√−πΌ + 5π½π‘) −15π½ ) π’1π = π√ ( 2πΎ (1 ± sec (π₯ + π√−πΌ + 5π½π‘)) + π√ π΅ = 0, 2 (9e) −15π½ , 2πΎ −15π½ (cot (π₯ + π√−πΌ + 5π½π‘) 2πΎ 2 ± csc (π₯ + π√−πΌ + 5π½π‘)) (8f) where π΄, π΅, and πΆ are arbitrary constants, while πΆ cannot be zero in Cases 1 and 2 and π΄ cannot be zero in Cases 3–6. π is an arbitrary element of {−1, 1}. (9b) −15π½ (tan (π₯ + π√−πΌ + 5π½π‘) 2πΎ πΏ = −4π΄2 πΆ2 π½ (13 ± √165) , π2 = 0, −15π½ , 2πΎ tanh (π₯ + π√−πΌ − 5π½π‘) −15π½ ) π’1π = π√ ( 2πΎ (1 ± sech (π₯ + π√−πΌ − 5π½π‘)) π΅ = 0, π = π√−πΌ + (−30 ± 2√165) πΆπ΄π½, π−1 = 0, (9a) π΅ = 0, 2 π = ±√−πΌ − 60πΆπ΄π½, 30π½ , πΎ Substituting ((8a), (8b), (8c), (8d), (8e), (8f)) into (6) respectively and taking advantage of solitions to (5), we can find the following solutions which contain multiple solitionlike and triangular periodic solutions for the generalized Bretherton equation. When πΏ = 4π½, + π√ −15π½ , 2πΎ (9f) 4 Abstract and Applied Analysis π’1π = π√ when πΏ = 1024π½, −15π½ (sec (π₯ + π√−πΌ + 5π½π‘) 2πΎ 2 − tan (π₯ + π√−πΌ + 5π½π‘)) + π√ π’1β (9g) −15π½ , 2πΎ − 8π√ cot (π₯ + π√−πΌ + 5π½π‘) −15π½ ) = π√ ( 2πΎ (1 ± csc (π₯ + π√−πΌ + 5π½π‘)) tan (π₯ ± √−πΌ + 80π½π‘) −30π½ ) ( πΎ (1 − tan2 (π₯ ± √−πΌ + 80π½π‘)) + 8π√ −30π½ −30π½ coth2 (π₯ ± √−πΌ − 20π½π‘) − 2π√ , πΎ πΎ (10b) −30π½ 2 −30π½ tan (π₯ ± √−πΌ + 20π½π‘) + 2π√ , πΎ πΎ (10c) π’2π = 2π√ 2 π’3π = 32π√ −30π½ −30π½ = 2π√ tanh2 (π₯ ± √−πΌ − 20π½π‘) − 2π√ , πΎ πΎ (10a) π’2π = 2π√ −30π½ 2 −30π½ cot (π₯ ± √−πΌ + 20π½π‘) + 2π√ , πΎ πΎ (10d) + 4π√ π’2π = 8π√ π’4 = β 8π√ −30π½ cot (π₯ + π√−πΌ + 20π½π‘) πΎ (1 ± cot (π₯ + π√−πΌ + 20π½π‘)) + 4π√ −30π½ , πΎ ±2√−30π½/πΎ 2 ((π₯ + π√−πΌπ‘) + π0 ) 2 . (12) When πΏ = −π½, π’5π = π√ 15π½ (coth (π₯ + π√−πΌ + 15π½π‘) 2πΎ ± csch (π₯ + π√−πΌ + 15π½π‘)) (10e) −2 (13a) 15π½ , 2πΎ −2 tanh (π₯ + π√−πΌ + 15π½π‘) 15π½ ) π’5π = π√ ( 2πΎ (1 ± sech (π₯ + π√−πΌ + 15π½π‘)) −30π½ , πΎ cot (π₯ + π√−πΌ + 20π½π‘) −30π½ ) ( πΎ (1 ± cot (π₯ + π√−πΌ + 20π½π‘)) (11c) when πΏ = 0, − π√ −30π½ πΎ (1 ± tan (π₯ + π√−πΌ + 20π½π‘)) 2 −30π½ + 8π√ , πΎ 2 tan (π₯ + π√−πΌ + 20π½π‘) (11b) −30π½ , πΎ cot (π₯ ± √−πΌ + 80π½π‘) −30π½ ) π’3π = 32π√ ( πΎ (1 − cot2 (π₯ ± √−πΌ + 80π½π‘)) tan (π₯ + π√−πΌ + 20π½π‘) −30π½ ) π’2π = 8π√ ( πΎ (1 ± tan (π₯ + π√−πΌ + 20π½π‘)) β 8π√ −30π½ , πΎ (11a) (9h) when πΏ = 64π½, π’2π = 2π√ 2 2 −15π½ + π√ , 2πΎ π’2π π’3π tanh (π₯ ± √−πΌ − 80π½π‘) −30π½ ) = 32π√ ( πΎ (1 + tanh2 (π₯ ± √−πΌ − 80π½π‘)) − π√ 2 π’5π = π√ (13b) 15π½ , 2πΎ 15π½ (tan (π₯ + π√−πΌ − 15π½π‘) 2πΎ (10f) ± sec (π₯ + π√−πΌ − 15π½π‘)) + π√ 15π½ , 2πΎ −2 (13c) Abstract and Applied Analysis 5 −2 π’5π tan (π₯ + π√−πΌ − 15π½π‘) 15π½ ) = π√ ( 2πΎ (1 ± sec (π₯ + π√−πΌ − 15π½π‘)) + π√ π’5π = π√ 15π½ , 2πΎ − 8π√ 15π½ (cot (π₯ + π√−πΌ − 15π½π‘) 2πΎ + π√ π’7π = 2π√ (13e) −2 (13f) π’6π = 2π√ (15c) 15π½ 2πΎ 1 (−30 + 2π√165) π½π‘) 4 ± csch (π₯ + π√ −πΌ − −2 (13g) 30π½ 30π½ tanh−2 (π₯ ± √−πΌ + 60π½π‘) − 2π√ , πΎ πΎ (14a) 30π½ 30π½ coth−2 (π₯ ± √−πΌ + 60π½π‘) − 2π√ , πΎ πΎ (14b) 30π½ −2 30π½ tan (π₯ ± √−πΌ − 60π½π‘) + 2π√ , (14c) πΎ πΎ 30π½ −2 30π½ cot (π₯ ± √−πΌ − 60π½π‘) + 2π√ , (14d) πΎ πΎ when πΏ = −64π½, −2 1 (−30 + 2π√165) π½π‘)) 4 √165 30π½ 1 + π√ (−1 + π ), 4 πΎ 15 (16a) π’8π = π√ when πΏ = −16π½, π’6π = 2π√ −2 30π½ , πΎ × (coth (π₯ + π√ −πΌ − 15π½ , 2πΎ −15π½ + π√ , 2πΎ π’6π = 2π√ cot (π₯ ± √−πΌ − 240π½π‘) 30π½ ) ( πΎ (1 − cot2 (π₯ ± √−πΌ − 240π½π‘)) + 8π√ π’8π = π√ cot (π₯ + π√−πΌ − 15π½π‘) 15π½ ) = π√ ( 2πΎ (1 ± csc (π₯ + π√−πΌ − 15π½π‘)) π’6π = 2π√ 30π½ , πΎ when πΏ = −(13 ± √165)π½, 15π½ (sec (π₯ + π√−πΌ − 15π½π‘) 2πΎ + π√ π’5π −2 15π½ , 2πΎ − tan (π₯ + π√−πΌ − 15π½π‘)) −2 (15b) ± csc (π₯ + π√−πΌ − 15π½π‘)) π’5π = π√ (13d) tanh (π₯ ± √−πΌ + 240π½π‘) 30π½ ) ( π’7π = 2π√ πΎ (1 + tanh2 (π₯ ± √−πΌ + 240π½π‘)) 15π½ 2πΎ −2 tanh (π₯ + π√−πΌ − (1/4) (−30 + 2π√165) π½π‘) ×( ) (1± sech(π₯ +π√−πΌ − (1/4) (−30 + 2π√165) π½π‘)) √165 30π½ 1 + π√ (−1 + π ), 4 πΎ 15 (16b) π’8π = π√ 15π½ 1 (tan (π₯ + π√ −πΌ + (−30 + 2π√165) π½π‘) 2πΎ 4 1 ± sec (π₯+π√ −πΌ+ (−30+2π√165) π½π‘)) 4 −2 √165 30π½ 1 − π√ (−1 + π ), 4 πΎ 15 (16c) π’7π = 2π√ tanh (π₯ ± √−πΌ − 240π½π‘) 30π½ ) ( πΎ (1 − tanh2 (π₯ ± √−πΌ − 240π½π‘)) + 8π√ 30π½ , πΎ −2 π’8π = π√ (15a) 15π½ 2πΎ × (csc (π₯ + π√ −πΌ + 1 (−30 + 2π√165) π½π‘) 4 6 Abstract and Applied Analysis 1 − cot (π₯+ π√ −πΌ+ (−30 +2π√165) π½π‘)) 4 −2 when πΏ = −4(13 ± √165)π½, √165 30π½ 1 − π√ (−1 + π ), 4 πΎ 15 π’9π = 2π√ (16d) 30π½ tanh−2 (π₯ + π√−πΌ − (−30 + 2π√165) π½π‘) πΎ + π√ √165 30π½ (−1 + π ), πΎ 15 (17a) π’8π = π√ 15π½ 2πΎ π’9π = 2π√ tan (π₯ + π√−πΌ + (1/4) (−30+ 2π√165) π½π‘) −2 + π√ ) ×( (1± sec (π₯ + π√−πΌ + (1/4) (−30+ 2π√165) π½π‘)) π’9π = 2π√ (16e) 30π½ −2 tan (π₯ + π√−πΌ + (−30 + 2π√165) π½π‘) πΎ − π√ 15π½ 2πΎ × (cot (π₯ + π√ −πΌ + √165 30π½ (−1 + π ), πΎ 15 (17b) √165 30π½ 1 − π√ (−1 + π ), 4 πΎ 15 π’8π = π√ 30π½ coth−2 (π₯ + π√−πΌ − (−30 + 2π√165) π½π‘) πΎ √165 30π½ (−1 + π ), πΎ 15 (17c) 1 (−30 + 2π√165) π½π‘) 4 ± csc (π₯ + π√ −πΌ + π’9π = 2π√ 30π½ −2 cot (π₯ + π√−πΌ + (−30 + 2π√165) π½π‘) πΎ −2 1 (−30 + 2π√165) π½π‘)) 4 − π√ √165 30π½ (−1 + π ), πΎ 15 (17d) √165 30π½ 1 − π√ (−1 + π ), 4 πΎ 15 when πΏ = −64(13 ± √165)π½, (16f) π’8π = π√ π’10π 15π½ 2πΎ × (sec (π₯ + π√ −πΌ + = 2π√ 1 (−30 + 2π√165) π½π‘) 4 − tan (π₯ + π√ −πΌ + 1 (−30 + 2π√165) π½π‘)) 4 −2 √165 30π½ 1 − π√ (−1 + π ), 4 πΎ 15 30π½ πΎ −2 tanh (π₯ + π√−πΌ − 4 (−30 + 2π√165) π½π‘) ×( ) (1 + tanh2 (π₯ + π√−πΌ − 4 (−30 + 2π√165) π½π‘)) + 4π√ √165 30π½ (−1 + π ), πΎ 15 (16g) (18a) π’10π π’8β = π√ 15π½ 2πΎ = 2π√ cot (π₯ + π√−πΌ + (1/4) (−30 + 2π√165) π½π‘) 30π½ πΎ −2 tanh (π₯ + π√−πΌ + 4 (−30 + 2π√165) π½π‘) −2 ) ×( (1± csc (π₯ + π√−πΌ + (1/4) (−30+ 2π√165) π½π‘)) ×( ) (1 − tanh2 (π₯ + π√−πΌ + 4 (−30 + 2π√165) π½π‘)) √165 30π½ 1 − π√ (−1 + π ), 4 πΎ 15 − 4π√ (16h) √165 30π½ (−1 + π ), πΎ 15 (18b) Abstract and Applied Analysis 7 π’10π = 2π√ 30π½ πΎ cot (π₯ + π√−πΌ + 4 (−30 + 2π√165) π½π‘) −2 ×( ) (1 − cot2 (π₯+ π√−πΌ + 4 (−30 + 2π√165) π½π‘)) − 4π√ √165 30π½ (−1 + π ), πΎ 15 (18c) where π, π, and π are arbitrary elements of {−1, 1}. 3. 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