Hindawi Publishing Corporation Abstract and Applied Analysis Volume 2013, Article ID 767254, 5 pages http://dx.doi.org/10.1155/2013/767254 Research Article The Multisoliton Solutions for the (2 + 1)-Dimensional Sawada-Kotera Equation Zhenhui Xu,1 Hanlin Chen,2 and Wei Chen3 1 Applied Technology College, Southwest University of Science and Technology, Mianyang 621010, China School of Science, Southwest University of Science and Technology, Mianyang 621010, China 3 School of Mathematics and Computer Science, Mianyang Normal University, Mianyang 621000, China 2 Correspondence should be addressed to Zhenhui Xu; xuzhenhui19@163.com Received 13 November 2012; Revised 19 December 2012; Accepted 1 January 2013 Academic Editor: Lan Xu Copyright © 2013 Zhenhui Xu 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. Applying bilinear form and extended three-wavetype of ansaΜtz approach on the (2 + 1)-dimensional Sawada-Kotera equation, we obtain new multisoliton solutions, including the double periodic-type three-wave solutions, the breather two-soliton solutions, the double breather soliton solutions, and the three-solitary solutions. These results show that the high-dimensional nonlinear evolution equation has rich dynamical behavior. 1. Introduction As is well known that the exact solutions of nonlinear evolution equations play an important role in nonlinear science field, especially in nonlinear physical science since they can provide much physical information and more insight into the physical aspects of the problem and thus lead to further applications. The search for exact solutions of nonlinear partial differential equations has long been an interesting and hot topic in nonlinear mathematical physics. Consequently, many methods are available to look for exact solutions of nonlinear evolution equations, such as the inverse scattering method, the Lie group method, the mapping method, Exp-function method, and ansaΜtz technique [1–4]. Very recently, Wang et al. [5] proposed a new technique called extended threewave approach to seek multiwave solutions for integrable equations, and this method has been used to investigate several equations [6, 7]. In this paper, we consider the following Sawada-Kotera equation: 5 π’π‘ = (π’π₯π₯π₯π₯ + 5π’π’π₯π₯ + π’3 + 5π’π₯π¦ ) 3 π₯ − 5 ∫ (π’π¦π¦ ) ππ₯ + 5π’π’π¦ + 5π’π₯ ∫ (π’π¦ ) ππ₯. Equation (1) was derived by B. G. Konopelchenko and V. G. Dubrovsky, and was called the Sawada-Kotera (SK) equation; for example, see [8]. By means of the two-soliton method, the exact periodic soliton solutions, N-soliton solutions, and traveling wave solutions of the SK equation were found [8– 10]. In this paper, we discuss further the (2 + 1)-dimensional SK equation, by using bilinear form and extended three-wave type of ansaΜtz approach, respectively [5, 11–15], and some new multisoliton solutions are obtained. 2. The Multisoliton Solutions We assume π’ = −2(ln π)π₯π₯ , (2) where π = π(π₯, π¦, π‘) is an unknown real function. Substituting (2) into (1), we can reduce (1) into the following equation [8]: (1) (π·π₯6 + 5π·π¦ π·π₯3 − 5π·π¦2 + π·π₯ π·π‘ ) π ⋅ π = 0, (3) 2 Abstract and Applied Analysis where the Hirota bilinear operator π· is defined by (π, π ≥ 0) π·π₯π π·π‘π π (π₯, π‘) ⋅ π (π₯, π‘) π π π π π π − ) ( − σΈ ) ππ₯ ππ₯σΈ ππ‘ ππ‘ σ΅¨ × [π (π₯, π‘) π (π₯σΈ , π‘σΈ )]σ΅¨σ΅¨σ΅¨σ΅¨π₯σΈ =π₯,π‘σΈ =π‘ . =( (4) Substituting (7) into (2) yields the three-soliton solution of SK equation as follows: 1 π’1 = − (2 [2√πΏ3 π12 cosh (π1 + ln (πΏ3 )) 2 − πΏ1 π12 π32 cosh (π1 ) ]) π12 −π32 × (2√πΏ3 cosh (π1 + Now we suppose the solution of (3) as 1 ln (πΏ3 )) 2 −1 π = π−π + πΏ1 cos (π) + πΏ2 cosh (πΎ) + πΏ3 ππ , (5) where π = π1 π₯ + π1 π¦ + π1 π‘, π = π2 π₯ + π2 π¦ + π2 π‘, πΎ = π3 π₯ + π3 π¦ + π3 π‘, and ππ , ππ , and ππ (π = 1, 2, 3) are some constants to be determined later. Substituting (5) into (3) and equating all the coefficients of different powers of ππ , π−π , sin(π), cos(π), sinh(πΎ), cosh(πΎ), and the constant term to zero, we can obtain a set of algebraic equations for ππ , ππ , ππ , and πΏπ (π = 1, 2, 3; π = 1, 2, 3). Solving the system with the aid of Maple, we get the following results. − − πΏ1 π12 π3 sinh (π1 ) )) (π12 −π32 ) × (2√πΏ3 cosh (π1 + 1 ln (πΏ3 )) 2 −1 2 1 π1 = − π1 (4π12 + 3π32 ) , 4 1 π3 = − π3 (6π12 + π32 ) , 4 π2 = πΏ2 = πΏ π2 cosh (π1 ) − πΏ1 cosh (πΎ1 )) ] , − 1 12 π1 − π32 3 2 ππ π , 2 1 3 where π1 = π1 π₯ + πΎ1 π¦ + πΏ 1 π‘, π1 = π3 π₯ − π»1 π¦ + π½1 π‘, and πΎ1 = π1 π¦ + π1 π‘. If taking π3 = ππ΄ 3 in (7), then we have πΏ π2 − 21 1 2, π1 − π3 πΏ3 = πΏ3 , 9 π1 = π1 (5π34 + 40π12 π32 + 16π14 ) , 16 π3 = (8) 1 + [ (2 (2√πΏ3 π1 sinh (π1 + ln (πΏ3 )) 2 Case 1. If π2 = 0, then π2 = − πΏ1 π12 cosh (π1 ) − πΏ1 cosh (πΎ1 )) π12 − π32 (6) − 9 π (π4 + 20π12 π32 + 40π14 ) , 16 3 3 where π1 , π3 , πΏ1 , and πΏ3 are free real constants. Substituting (6) into (5) and taking πΏ3 > 0, we have − πΏ1 cosh (π1 π¦ + π1 π‘) − 1 ln (πΏ3 )) 2 πΏ1 π12 π12 − π32 1 ln (πΏ3 )) 2 + πΏ1 cos (π2 π¦ + π2 π‘) 45 2 ππ π (2π12 + π32 ) , 4 1 3 π1 = 2√πΏ3 cosh (π1 π₯ + πΎ1 π¦ + πΏ 1 π‘ + π2 = 2√πΏ3 cosh (π1 π₯ + πΎ2 π¦ + πΏ 2 π‘ + πΏ1 π12 cos (π΄ 3 π₯ − π»2 π¦ + π½2 π‘) , π12 + π΄23 where πΏ3 > 0, πΎ2 = −(1/4)π1 (4π12 −3π΄23 ), πΏ 2 = (9/16)π1 (5π΄43 − 40π12 π΄23 + 16π14 ), π2 = (3/2)π12 π΄ 3 , π2 = −(45/4)π12 π΄ 3 (2π12 − π΄23 ), π»2 = π΄ 3 π₯ − (1/4)π΄ 3 (6π12 − π΄23 ), and π½2 = (9/16)π΄ 3 (π΄43 − 20π12 π΄23 + 40π14 ). Substituting (9) into (2) yields the double breather soliton solution of SK equation as follows: π’2 = − (2 [2π12 √πΏ3 cosh (π2 + (7) × cosh (π3 π₯ − π»1 π¦ + π½1 π‘) , where πΎ1 = (1/4)π1 (4π12 + 3π32 ), πΏ 1 = (9/16)π1 (5π34 + 40π12 π32 + 16π14 ), π1 = −(3/2)π12 π3 , π1 = (45/4)π12 π3 (2π12 + π32 ), π»1 = (1/4)π3 (6π12 + π32 ), and π½1 = (9/16)π3 (π34 + 20π12 π32 + 40π14 ). (9) + 1 ln (πΏ3 )) 2 πΏ1 π12 π΄23 cos (π2 ) ]) π12 + π΄23 × (2√πΏ3 cosh (π2 + 1 ln (πΏ3 )) 2 −1 +πΏ1 cos (πΎ2 ) − πΏ1 π12 cos (π2 ) ) π12 + π΄23 Abstract and Applied Analysis 3 1 ln (πΏ3 )) 2 + 2 [(2π1 √πΏ3 sinh (π2 + + The expression (π’3 ) is the breather two-soliton solution of SK equation which is a periodic wave in π₯, π¦ and meanwhile is a two-soliton in π₯, π¦ (refer to Figure 1(b)). πΏ1 π12 π΄ 3 sin (π2 ) ) π12 +π΄23 Case 3. If π2 = π1 = 0, then 1 × (2√πΏ3 cosh (π2 + ln (πΏ3 )) 2 π1 = 2π3 , π1 = − −1 2 πΏ1 π12 cos (π2 ) ) ], +πΏ1 cos (πΎ2 )− π12 +π΄23 where π2 = π1 π₯ + πΎ2 π¦ + πΏ 2 π‘, π2 = π΄ 3 π₯ − π»2 π¦ + π½2 π‘, and πΎ2 = π2 π¦ + π2 π‘. Case 2. If π2 =ΜΈ 0, then π1 = −π13 , π2 = π23 , πΏ1 = πΏ1 , π3 = −π33 , πΏ2 = πΏ2 , π1 = 9π15 , πΏ3 = πΏ3 , π2 = 9π25 , (11) π3 = 9π35 , π3 = 2√πΏ3 cosh (π1 π₯ − π13 π¦ + 9π15 π‘ + Substituting (12) into (2) yields the breather two-soliton solution of SK equation as follows: 1 ln (πΏ3 )) 2 −1 (13) 1 ln (πΏ3 )) 2 + + πΏ1 cos (−√21π33 π¦ + 20√21π35 π‘) (15) 1 ln (πΏ3 )) 2 π3 = π2 π₯ + where (5/152)πΏ22 − (7/228)πΏ12 > 0. Substituting (15) into (2) yields the breather two-soliton solution of SK equation as follows: π’4 = − (2 [8√πΎ4 π32 cosh (π4 − 1 ln (πΎ4 )) 2 1 ln (πΎ4 )) 2 −1 (16) 1 + 2 [ (4√πΎ4 π3 sinh (π4 − ln (πΎ4 )) 2 × (2√πΎ4 cosh (π4 − 1 ln (πΎ4 )) 2 −1 2 +πΏ1 cos (πΎ4 ) + πΏ2 cosh (π4 ) ) ] , −1 2 9π15 π‘, 169 5 1 7 2 5 2 π3 π‘ − ln ( πΏ2 − πΏ )) 2 2 152 228 1 +πΏ2 π3 sinh (π4 ) ) +πΏ1 cos (π3 ) + πΏ2 cosh (πΎ3 ) ) ] , where π3 = π1 π₯ − π13 π¦ πΎ3 = π3 π₯ − π33 π¦ + 9π35 π‘. 5 2 7 2 πΏ − πΏ 152 2 228 1 +πΏ1 cos (πΎ4 ) + πΏ2 cosh (π4 ) ) −πΏ1 π2 sin (π3 ) + πΏ2 π3 sinh (πΎ3 ) )) × (2√πΏ3 cosh (π3 + π4 = 2√ × (2√πΎ4 cosh (π4 − 1 ln (πΏ3 )) 2 + [ (2 (2√πΏ3 π1 sinh (π3 + where π3 , πΏ1 , and πΏ2 are free real constants. Substituting (14) into (5) and taking πΏ3 > 0, we have +πΏ2 π32 cosh (π4 ) ]) −πΏ1 π22 cos (π3 ) + πΏ2 π32 cosh (πΎ3 ) ]) +πΏ1 cos (π3 ) + πΏ2 cosh (πΎ3 ) ) (14) 5 2 7 2 πΏ2 − πΏ, 152 228 1 (12) + πΏ2 cosh (π3 π₯ − π33 π¦ + 9π35 π‘) . × (2√πΏ3 cosh (π3 + 349 5 π3 = − π, 4 3 3 349 5 + πΏ2 cosh (−π3 π₯ + π3 3 π¦ + π π‘) , 2 4 3 1 ln (πΏ3 )) 2 + πΏ1 cos (π2 π₯ + π23 π¦ + 9π25 π‘) π’3 = − (2 [2√πΏ3 π12 cosh (π3 + πΏ3 = × cosh (−2π3 π₯ + where π1 , π2 , π3 , πΏ1 , πΏ2 , and πΏ3 are free real constants. Substituting (11) into (5) and taking πΏ3 > 0, we have 169 5 π, 2 3 π2 = −20√21π35 , (10) 3 π3 = − π33 , 2 π2 = √21π33 , π23 π¦ + 9π25 π‘, and where πΎ4 = (5/152)πΏ22 − (7/228)πΏ12 , π4 = −2π3 π₯ + (169/2)π35 π‘, π4 = −π3 π₯ + (3/2)π33 π¦ + (349/4)π35 π‘, and πΎ4 = −√21π33 π¦ + 20√21π35 π‘. Abstract and Applied Analysis −0.06 −0.04 −0.02 0 −20 0 −1 −2 π’3 π’2 4 −10 0 π¦ 10 20 −20 30 −30 −10 10 0 20 −3 −4 −5 −10 π₯ −5 π¦ 0 (a) 0 4 π₯ 120000 −2 100000 −4 π’5 π’4 10 8 −8 (b) 0 −6 −8 −3 −2 5 −4 80000 60000 40000 20000 0 −1 π¦ 0 −4 1 2 3 2 4 0 −2 −4 −2 π₯ π₯ 0 (c) 2 4 −4 −2 0 2 4 π¦ (d) Figure 1: (a) The figure of π’2 as πΏ1 = 1, πΏ3 = 1, and π‘ = 1. (b) The figure of π’3 as πΏ1 = √2, πΏ2 = 1, and π‘ = 0. (c) The figure of π’4 as πΏ1 = √2, πΏ2 = √5, and π‘ = 0.005. (d) The figure of π’5 as πΏ1 = 1, πΏ2 = 1, and π‘ = 0. The expression (π’4 ) is the breather two-soliton solution of SK equation which is a periodic wave in π¦-π‘ and meanwhile is a two-soliton in π₯, π¦ and in π₯-π‘, respectively (refer to Figure 1(c)). Notice that π’3 and π’4 are also the breather two-soliton solutions, but their structure is different, because the two wave propagation directions are different in the π’3 and π’4 , respectively (refer to Figures 1(b) and 1(c)). If taking π1 = ππ΄ 1 , π3 = ππ΄ 3 in (12), then we have π5 = 2 cos (π΄ 1 π₯ + π΄31 π¦ + + πΏ2 cos (π΄ 3 π₯ + π΄33 π¦ + 9π΄53 π‘) , π’5 = 2 [2π΄21 cos (π5 ) + πΏ1 π22 cos (π5 ) + πΏ2 π΄23 cos (πΎ5 )] 2 cos (π5 ) + πΏ1 cos (π5 ) + πΏ2 cos (πΎ5 ) 2 + 2[ 2π΄ 1 sin (π5 ) + πΏ1 π2 sin (π5 ) + πΏ2 π΄ 3 sin (πΎ5 ) ], 2 cos (π5 ) + πΏ1 cos (π5 ) + πΏ2 cos (πΎ5 ) (18) where π5 = π΄ 1 π₯ + π΄31 π¦ + 9π΄51 π‘, π5 = π2 π₯ + π23 π¦ + 9π25 π‘, and πΎ5 = π΄ 3 π₯ + π΄33 π¦ + 9π΄53 π‘. 9π΄51 π‘) + πΏ1 cos (π2 π₯ + π23 π¦ + 9π25 π‘) when πΏ3 = 1. Substituting (17) into (2) gives the doubleperiodic three-wave solution of SK equation as follows: (17) 3. Conclusion By using bilinear form and extended three-wave type of ansaΜtz approach, we discuss further the (2 + 1)-dimensional Abstract and Applied Analysis Sawada-Kotera equation and find some new multisoliton solutions. The result shows that the extended three-wave type of ansaΜtz approach may provide us with a straightforward and effective mathematical tool for seeking multiwave solutions of high-dimensional nonlinear evolution equations. Acknowledgments This work was supported by Chinese Natural Science Foundation Grant nos. 11061028, 10971169. Sichuan Educational Science Foundation Grant no. 09zc008. References [1] M. J. Abolowitz and P. A. Clarkson, Solitons, Nonlinear Evolution Equations and Inverse Scattering Transform, Cambridge University Press, Cambridge, UK, 1991. [2] A. Maccari, “Chaos, solitons and fractals in the nonlinear Dirac equation,” Physics Letters A, vol. 336, no. 2-3, pp. 117–125, 2005. [3] Z. Feng, “Comment on ”On the extended applications of homogeneous balance method”,” Applied Mathematics and Computation, vol. 158, no. 2, pp. 593–596, 2004. [4] X. Q. Liu, H. L. Chen, and Y. Q. LuΜ, “Explicit solutions of the generalized KdV equations with higher order nonlinearity,” Applied Mathematics and Computation, vol. 171, no. 1, pp. 315– 319, 2005. [5] C. Wang, Z. Dai, and L. Liang, “Exact three-wave solution for higher dimensional KdV-type equation,” Applied Mathematics and Computation, vol. 216, no. 2, pp. 501–505, 2010. [6] Z. Dai, S. Lin, H. Fu, and X. Zeng, “Exact three-wave solutions for the KP equation,” Applied Mathematics and Computation, vol. 216, no. 5, pp. 1599–1604, 2010. [7] Z. Li and Z. Dai, “Exact periodic cross-kink wave solutions and breather type of two-solitary wave solutions for the (3 + 1)dimensional potential-YTSF equation,” Computers and Mathematics with Applications, vol. 61, no. 8, pp. 1939–1945, 2011. [8] H. Y. Ruan, “Interactions between two-periodic solitons in the (2 + 1)-dimensional Sawada-Kotera equations,” Acta Physica Sinica, vol. 53, no. 6, pp. 1618–1622, 2004. [9] H. M. Fu and Z. D. Dai, “Periodic soliton wave solutions for twodimension S-K equation,” Journal of Xuzhou Normal University, vol. 27, no. 4, pp. 20–22, 2009. [10] Z. Y. Wang and H. L. Lv, “Travelling wave solutions of (2 + 1)-dimensional Sawada-Kotera equation,” Journal of Liaocheng University, vol. 23, no. 4, 2010. [11] W. X. Ma and E. Fan, “Linear superposition principle applying to Hirota bilinear equations,” Computers and Mathematics with Applications, vol. 61, no. 4, pp. 950–959, 2011. [12] Z. Dai, J. Huang, M. Jiang, and S. Wang, “Homoclinic orbits and periodic solitons for Boussinesq equation with even constraint,” Chaos, Solitons and Fractals, vol. 26, no. 4, pp. 1189–1194, 2005. [13] Z. H. Xu, D. Q. Xian, and H. L. Chen, “New periodic solitarywave solutions for the Benjiamin Ono equation,” Applied Mathematics and Computation, vol. 215, no. 12, pp. 4439–4442, 2010. [14] Z. Dai, S. Li, Q. Dai, and J. Huang, “Singular periodic soliton solutions and resonance for the Kadomtsev-Petviashvili equation,” Chaos, Solitons and Fractals, vol. 34, no. 4, pp. 1148–1153, 2007. 5 [15] J. H. He, “Asymptotic methods for solitary solutions and compactons,” Abstract and Applied Analysis, vol. 2012, Article ID 916793, 130 pages, 2012. Advances in Operations Research Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Advances in Decision Sciences Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Mathematical Problems in Engineering Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Journal of Algebra Hindawi Publishing Corporation http://www.hindawi.com Probability and Statistics Volume 2014 The Scientific World Journal Hindawi Publishing Corporation http://www.hindawi.com Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 International Journal of Differential Equations Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Volume 2014 Submit your manuscripts at http://www.hindawi.com International Journal of Advances in Combinatorics Hindawi Publishing Corporation http://www.hindawi.com Mathematical Physics Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Journal of Complex Analysis Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 International Journal of Mathematics and Mathematical Sciences Journal of Hindawi Publishing Corporation http://www.hindawi.com Stochastic Analysis Abstract and Applied Analysis Hindawi Publishing Corporation http://www.hindawi.com Hindawi Publishing Corporation http://www.hindawi.com International Journal of Mathematics Volume 2014 Volume 2014 Discrete Dynamics in Nature and Society Volume 2014 Volume 2014 Journal of Journal of Discrete Mathematics Journal of Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Applied Mathematics Journal of Function Spaces Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Optimization Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 Hindawi Publishing Corporation http://www.hindawi.com Volume 2014