Microsoft Word - Md. and Ali.doc Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.58 (Online Publication: Dec., 2013) BIBECHANA A Multidisciplinary Journal of Science, Technology and Mathematics ISSN 2091-0762 (online) Journal homepage: http://nepjol.info/index.php/BIBECHANA Application of the new approach of generalized )/( GG′ -expansion method to find exact solutions of nonlinear PDEs in mathematical physics Md. Nur Alam 1 and M. Ali Akbar 2* 1 Department of Mathematics, Pabna University of Science and Technology, Bangladesh 2Department of Applied Mathematics, University of Rajshahi, Bangladesh * Email: ali_math74@yahoo.com Article history: Received 27 October, 2013; Accepted 17 November, 2013 Abstract The exact solutions of nonlinear evolution equations (NLEEs) play a crucial role to make known the internal mechanism of complex physical phenomena. In this article, we construct the traveling wave solutions of the Zakharov-Kuznetsov-Benjamin-Bona-Mahony (ZK-BBM) equation by means of the new approach of generalized )/( GG′ -expansion method. Abundant traveling wave solutions with arbitrary parameters are successfully obtained by this method and the wave solutions are expressed in terms of the hyperbolic, trigonometric, and rational functions. It is shown that the new approach of generalized )/( GG′ -expansion method is a powerful and concise mathematical tool for solving nonlinear partial differential equations. Keywords: New approach of generalized )/( GG′ -expansion method, ZK-BBM equation; homogeneous balance, traveling wave solutions, solitary wave solutions, nonlinear evolution equation. 1. Introduction Nonlinear phenomena arise in several aspects of physics as well as other natural and applied sciences. Essentially all the fundamental equations in physical sciences are nonlinear and, in general, such NLEEs are often very complicated to solve explicitly. The exact solutions of NLEEs play an important role in the study of nonlinear physical phenomena. Therefore, the powerful and efficient methods to find exact solutions of nonlinear equations still have drawn a lot of interest by diverse group of scientists. In the past three decades, there has been significant progress in the development of finding effective methods for obtaining exact solutions of NLEEs. These methods are the Exp- function method [1-3], the generalized Riccati equation [4], the Miura transformation [5], the Jacobi elliptic function expansion method [6, 7], the Hirota’s bilinear method [8], the sine-cosine method [9], the tanh-function method [10], the extended tanh-function method [11-12], the homogeneous balance method [13], the modified Exp-function method [14], the )/( GG′ -expansion method [15-22], the Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.59 (Online Publication: Dec., 2013) improved )/( GG′ -expansion method [23], the modified simple equation method [24-28], the inverse scattering transform [29] and so on. Recently, Naher and Abdullah [30] established a highly effective extension of the )/( GG′ expansion method, called the new generalized )/( GG′ expansion method to obtain exact traveling wave solutions of NLEEs. The aim of this article is to look for new study relating to the new generalized )/( GG′ expansion method for solving the renowned ZK-BBM equation to make obvious the effectiveness and usefulness of the method. The outline of this paper is organized as follows: In Section 2, we give the description of the new generalized )/( GG′ expansion method. In Section 3, we apply this method to the ZK-BBM equation. In Section 4, Discussions are given. Conclusions are given in Section 5. 2. Description of the new generalized ( / )G G′ -expansion method Let us consider a general nonlinear PDE in the form ),,,,,,( … xtttxxxt vvvvvvΦ , (1) where ),( txvv = is an unknown function, Φ is a polynomial in ),( txv and its derivatives in which highest order derivatives and nonlinear terms are involved and the subscripts stand for the partial derivatives. Step 1: We combine the real variables x and t by a complex variable η )(),( ηvtxv = , tVx ±=η , (2) where V is the speed of the traveling wave. The traveling wave transformation (2) converts Eq. (1) into an ordinary differential equation (ODE) for )(ηvv = : ),,,,( ⋯vvvv ′′′′′′ψ , (3) where ψ is a polynomial of v and its derivatives and the superscripts indicate the ordinary derivatives with respect to η . Step 2: According to possibility, Eq. (3) can be integrated term by term one or more times, yields constant(s) of integration. The integral constant may be zero, for simplicity. Step 3. Suppose the traveling wave solution of Eq. (3) can be expressed as follows: i N i i i N i i MdMdv − == +++= ∑∑ )()()( 10 βαη , (4) where either N α or N β may be zero, but could be zero simultaneously, i α ),,2,1,0( Ni ⋯= and i β ),,2,1( Ni ⋯= and d are arbitrary constants to be determined and )(ηM is )/()( GGM ′=η (5) where )(ηGG = satisfies the following auxiliary nonlinear ordinary differential equation: 0)( 22 =′−−′−′′ GCGEGBGGAG , (6) where the prime stands for derivative with respect to η ; A , B ,C and E are real parameters. Step 4: To determine the positive integer N , taking the homogeneous balance between the highest order nonlinear terms and the derivatives of the highest order appearing in Eq. (3). Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.60 (Online Publication: Dec., 2013) Step 5: Substitute Eq. (4) and Eq. (6) including Eq. (5) into Eq. (3) with the value of N obtained in Step 4, we obtain polynomials in N Md )( + ),2,1,0( ⋯=N and N Md −+ )( ),2,1,0( ⋯=N . Subsequently, we collect each coefficient of the resulted polynomials to zero, yields a set of algebraic equations for i α ),,2,1,0( Ni ⋯= and i β ),,2,1( Ni ⋯= , d and V . Step 6: Suppose that the value of the constants i α ),,2,1,0( Ni ⋯= , i β ),,2,1( Ni ⋯= , d and V can be found by solving the algebraic equations obtained in Step 5. Since the general solutions of Eq. (6) are known to us, inserting the values of i α ),,2,1,0( Ni ⋯= , i β ),,2,1( Ni ⋯= , d and V into Eq. (4), we obtain more general type and new exact traveling wave solutions of the nonlinear partial differential equation (1). Step 7: Using the general solution of Eq. (6), we have the following solutions of Eq. (5): Family 1: When ,0≠B CA −=ω and ,0)(42 >−+=Ω CAEB         Ω +        Ω         Ω +        Ω Ω +=      ′ = ηη ηη ωω η A C A C A C A C B G G M 2 sinh 2 cosh 2 cosh 2 sinh 22 )( 21 21 (7) Family 2: When ,0≠B CA −=ω and ,0)(42 <−+=Ω CAEB         Ω− +        Ω−         Ω− +        Ω− − Ω− +=      ′ = ηη ηη ωω η A C A C A C A C B G G M 2 sin 2 cos 2 cos 2 sin 22 )( 21 21 (8) Family 3: When ,0≠B CA −=ω and ,0)(42 =−+=Ω CAEB ηω η 21 2 2 )( CC CB G G M + +=      ′ = (9) Family 4: When ,0=B CA −=ω and ,0>=∆ Eω )sinh()cosh( )cosh()sinh( )( 21 21 ηη ηη ω η A C A C A C A C G G M ∆ + ∆ ∆ + ∆ ∆ =      ′ = (10) Family 5: When ,0=B CA −=ω and ,0<=∆ Eω )sin()cos( )cos()sin( )( 21 21 ηη ηη ω η A C A C A C A C G G M ∆− + ∆− ∆− + ∆− −∆− =      ′ = (11) 3. Application of the method In this section, we will put forth the new generalized )/( GG′ expansion method to construct many new and more general traveling wave solutions of the ZK-BBM equation. Let us consider the ZK- BBM equation, Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.61 (Online Publication: Dec., 2013) 02 =−−+ txxxxt bvvvavv . (12) We will use the traveling wave transformation Eq. (2) into the Eq. (12), which yields: 02)1( =′′′−′−′+ vVbvvavV . (13) Integrating Eq. (13) with respect to η once yields ,0)1( 2 =+′′−−+ KvVbvavV (14) where K is an integration constant which is to be determined. Taking the homogeneous balance between highest order nonlinear term 2 v and linear term of the highest order v ′′ in Eq. (14), we obtain 2=N . Therefore, the solution of Eq. (14) is of the form: ,)()()()()( 2 2 1 1 2 210 −− ++++++++= MdMdMdMdv ββαααη (15) where 21210 ,,,, ββααα and d are constants to be determined. Substituting Eq. (15) together with Eqs. (5) and (6) into Eq. (14), the left-hand side is converted into polynomials in ( )NMd + ,.......)2,1,0( =N and ( ) N Md −+ ),2,1( ⋯=N . We collect each coefficient of these resulted polynomials to zero yields a set of simultaneous algebraic equations (for simplicity, the equations are not presented here) for 0α , 1α , 2α , 1β , 2β d , K and V . Solving these algebraic equations with the help of computer algebra, we obtain following: Set 1: )2816( 4 1 44242242222222 4 VAAVBVbAEBVbEVb aA K ++−+−−−= ωω , )81212( 2 1 22222 20 bVBVAAbVEbVBdbVd aA +−−−+−= ωωωα , ,VV = (16) ),232( 6 2223 21 EBdBEdBdd aA bV −+−+= ωωωβ ,dd = ,01 =α ,02 =α )222( 6 2222324 22 EdBBdEEdbdd aA bV ++−−+−= ωωωβ . where ,CA −=ω ,V ,d ,A ,B ,C E are free parameters. Set 2: )2816( 4 1 44242242222222 4 VAAVBVbAEBVbEVb aA K ++−+−−−= ωω , )81212( 2 1 22222 20 bVBVAAbVEbVBdbVd aA +−−−+−= ωωωα , ,VV = (17) )2( 6 2 21 ωωα Bd aA bV += , 2 2 2 6 aA bVω α −= , ,01 =β 02 =β . where ,CA −=ω ,V ,d ,A ,B ,C E are free parameters. Set 3: )16128256)1(( 4 1 4222222222242 4 BVbEBVbEAVbAV aA K −−−+−= ωω , )28)1(( 2 1 22 20 bVBbVEAV aA +++= ωα , 2 2 2 6 aA bVω α −= , ,01 =α ,VV = Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.62 (Online Publication: Dec., 2013) ),816( 8 3 4222 222 BEBE aA bV ++−= ωω ω β ,01 =β ω2 B d −= (18) where ,CA −=ω ,V ,A ,B ,C E are free parameters. For set 1, substituting Eq. (16) into Eq. (15), along with Eq. (7) and simplifying, yields following traveling wave solutions, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: 2 2 1 101 )) 2 coth( 22 ()) 2 coth( 22 ()( 1 −− ΩΩ +++ ΩΩ +++= η ωω βη ωω βαη A B d A B dv . 2 2 1 101 )) 2 tanh( 22 ()) 2 tanh( 22 ()( 2 −− ΩΩ +++ ΩΩ +++= η ωω βη ωω βαη A B d A B dv . Substituting Eq. (16) into Eq. (15), along with Eq. (8) and simplifying, our exact solutions become, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: 2 2 1 101 )) 2 cot( 22 ()) 2 cot( 22 ()( 3 −− Ω−Ω− +++ Ω−Ω− +++= η ωω βη ωω βαη A B d A B dv . 2 2 1 101 )) 2 tan( 22 ()) 2 tan( 22 ()( 4 −− Ω−Ω− −++ Ω−Ω− −++= η ωω βη ωω βαη A B d A B dv . Substituting Eq. (16) into Eq. (15), together with Eq. (9) and simplifying, our obtained solution becomes: .) 2 () 2 ()( 2 21 2 2 1 21 2 1015 −− + +++ + +++= ηω β ηω βαη CC CB d CC CB dv Substituting Eq. (16) into Eq. (15), along with Eq. (10) and simplifying, we obtain following traveling wave solutions, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: .))coth(())coth(()( 2 2 1 1016 −− ∆∆ ++ ∆∆ ++= η ω βη ω βαη A d A dv 2 2 1 101 ))tanh(())tanh(()( 7 −− ∆∆ ++ ∆∆ ++= η ω βη ω βαη A d A dv . Substituting Eq. (16) into Eq. (15), together with Eq. (11) and simplifying, our obtained exact solutions become, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: 2 2 1 101 ))cot(())cot(()( 8 −− ∆−∆− ++ ∆−∆− ++= η ω βη ω βαη A d A dv 2 2 1 101 ))tan(())tan(()( 9 −− ∆−∆− −+ ∆−∆− −+= η ω βη ω βαη A d A dv , where .Vtx −=η Again for set 2, substituting Eq. (17) into Eq. (15), along with Eq. (7) and simplifying, our traveling wave solutions become, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.63 (Online Publication: Dec., 2013) )), 2 (coth3)1()4(2( 2 1 )( 222 221 ηωη A bVVAEBbV aA v Ω Ω−+++= )), 2 (tanh3)1()4(2( 2 1 )( 222 222 ηωη A bVVAEBbV aA v Ω Ω−+++= Substituting Eq. (17) into Eq. (15), along with Eq. (8) and simplifying yields exact solutions, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: )), 2 (cot3)1()4(2( 2 1 )( 222 223 ηωη A bVVAEBbV aA v Ω− Ω++++= )) 2 (tan3)1()4(2( 2 1 )( 222 224 ηωη A bVVAEBbV aA v Ω− Ω++++= . Substituting Eq. (17) into Eq. (15), along with Eq. (9) and simplifying, our obtained solution becomes: ),)(12)1()4(2( 2 1 )( 2 21 2222 225 η ωωη CC C bVVAEBbV aA v + −+++= Substituting Eq. (17) into Eq. (15), together with Eq. (10) and simplifying, yields following traveling wave solutions, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: )))(coth)coth((12)1()8(( 2 1 )( 222 226 ηηωη AA BbVVAEBbV aA v ∆ ∆− ∆ ∆++++−= . )))(tanh)tanh((12)1()8(( 2 1 )( 222 227 ηηωη AA BbVVAEBbV aA v ∆ ∆− ∆ ∆++++−= . Substituting Eq. (17) into Eq. (15), along with Eq. (11) and simplifying, our exact solutions become, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: ))).(cot)cot((12)1()8(( 2 1 )( 222 228 ηηωη AA iBbVVAEBbV aA v ∆− ∆+ ∆− ∆++++−= ))(tan)tan((12)1()8(( 2 1 )( 222 229 ηηωη AA iBbVVAEBbV aA v ∆− ∆− ∆− ∆−+++−= , where .Vtx −=η Similarly, for set 3, substituting Eq. (18) into Eq. (15), together with Eq. (7) and simplifying, yields following traveling wave solutions, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: ) 2 (tanh 4 ) 2 (coth 2 3 )( 2 2 22 2031 η ω ηαη A b AaA bV v Ω Ω + ΩΩ −= . ) 2 (coth 4 ) 2 (tanh 2 3 )( 2 2 22 2032 η ω ηαη A b AaA bV v Ω Ω + ΩΩ −= . Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.64 (Online Publication: Dec., 2013) Substituting Eq. (18) into Eq. (15), along with Eq. (8) and simplifying, we obtain following solutions, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: ) 2 (tan 4 ) 2 (cot 2 3 )( 2 2 22 2033 η ω ηαη A b AaA bV v Ω− Ω − Ω−Ω += . ) 2 (cot 4 ) 2 (tan 2 3 )( 2 2 22 2034 η ω ηαξ A b AaA bV v Ω− Ω − Ω−Ω += . Substituting Eq. (18) into Eq. (15), along with Eq. (9) and simplifying, our obtained solution becomes: .)()( 6 )( 2 21 2 2 2 21 2 2 2 035 − + + + −= η β η ω αη CC C CC C aA bV v Substituting Eq. (18) into Eq. (15), along with Eq. (10) and simplifying, yields following exact traveling wave solutions, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: 2 2 2 2 2 03 ))coth( 2 ())coth( 2 ( 6 )( 6 −∆∆ + − + ∆∆ + − −= η ωω βη ωω ω αη A B A B aA bV v . 2 2 2 2 2 03 ))tanh( 2 ())tanh( 2 ( 6 )( 7 −∆∆ + − + ∆∆ + − −= η ωω βη ωω ω η A B A B aA bV av . Substituting Eq. (18) into Eq. (15), along with Eq. (11) and simplifying, our obtained exact solutions become, if 01 =C but ;02 ≠C 02 =C but 01 ≠C respectively: 2 2 2 2 2 03 ))cot( 2 ())cot( 2 ( 6 )( 8 −∆−∆− + − + ∆−∆− + − −= η ωω βη ωω ω αη A B A B aA bV v . 2 2 2 2 2 03 ))tan( 2 ())tan( 2 ( 6 )( 9 −∆−∆− − − + ∆−∆− − − −= η ωω βη ωω ω αη A B A B aA bV v . where .Vtx −=η 4. Discussions The advantages and validity of the method over the basic )/( GG′ -expansion method and the generalized and improved )/( GG′ -expansion method have been discussed in the following. Advantages: The crucial advantage of the new approach against the basic )/( GG′ -expansion method and the generalized and improved )/( GG′ -expansion method is that the method provides more general and abundant new exact traveling wave solutions with many real parameters. The exact solutions have its great importance to expose the inner mechanism of the complex physical phenomena. Apart from the physical application, the close-form solutions of nonlinear evolution equations assist the numerical solvers to compare the correctness of their results and help them in the stability analysis. Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.65 (Online Publication: Dec., 2013) Validity: In Ref. [31] Zhang et al. used the linear ordinary differential equation (LODE) as auxiliary equation and traveling wave solutions presented in the form ∑ −= ′= m mi i i GGau ,)/()(ξ where 0≠ m a . Akbar et al. [17] used same auxiliary equation (LODE) and the solution is presented in the form ∑ −= − ′+ = m mn n n GGd e u , ))/(( )(ξ where either m e− or m e may be zero, but both m e− or m e cannot be zero together. It is noteworthy to point out that some of our solutions are coincided with previously published results, if the parameters are taken particular values which validate our solutions. Moreover, In Ref. [31] Zhang et al. investigated the ZK-BBM equation to obtain exact solutions via the improved )/( GG′ -expansion method and achieved only six solutions (A.1)-(A.6) (see appendix A). On the other hand, by using the generalized and improved )/( GG′ -expansion method, Akbar et al. [17] obtained nine solutions (B.1)-(B.9) (see appendix B) of the ZK-BBM equation. But in this article twenty seven exact solutions including (A.1)-(A.6) and (B.1)-(B.2) of the ZK-BBM equation are constructed by applying the new approach of generalized )/( GG′ -expansion method. 5. Conclusion In this study, we considered the Zakharov-Kuznetsov-Benjamin-Bona-Mahony (ZK-BBM) equation. We employed the new approach of generalized )/( GG′ -expansion method for the exact solution to this equation and constructed some new solutions which are not found in the previous literature. The method offers solutions with free parameters that might be imperative to explain some intricate physical phenomena. This study shows that the new generalized )/( GG′ -expansion method is quite efficient and practically well suited to be used in finding exact solutions of NLEEs. Also, we observe that the new generalized )/( GG′ -expansion method is straightforward and can be applied to many other nonlinear evolution equations. References 1. J.H. He and X.H. Wu, Chaos, Solitons Fract., 30 (2006) 700. 2. M.A. Akbar and N.H.M. Ali, World Appl. Sci. J., 17(12) (2012) 1603. 3. H. Naher, A.F. Abdullah and M.A. Akbar, J. Appl. Math., Article ID 575387 (2012) 14 pages. doi: 10.1155/2012/575387. 4. 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A, 372 (2008) 3400. Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.66 (Online Publication: Dec., 2013) 19. E.M.E. Zayed, J. Appl. Math. Comput., 30 (2009) 89. 20. M.A. Akbar, N.H.M. Ali and S.T. Mohyud-Din, World Appl. Sci. J., 16(11) (2012) 1551. 21. M.A. Akbar, N.H.M. Ali and S.T. Mohyud-Din, J. Comput. Analysis Appl., 15(3) (2013) 557. 22. S. Zhang, J. Tong and W. Wang, Phys. Lett. A, 372 (2008) 2254. 23. J. Zhang, F. Jiang and X. Zhao, Int. J. Com. Math., 87(8) (2010) 1716. 24. A.J.M. Jawad, M.D. Petkovic and A. Biswas, Appl. Math. Comput., 217 (2010) 869. 25. E.M.E. Zayed, Appl. Math. Comput., 218 (2011) 3962. 26. E.M.E. Zayed and S.A.H. Ibrahim, Chin. Phys. Lett., 29 (06) (2012) 060201. 27. K. Khan and M.A. Akbar, Ain Shams Engr. J., 4(4) (2013) 903. 28. K. Khan, M.A. Akbar and N.H.M. Ali, ISRN Math. Phys., Vol. (2013), Article ID 146704, 5 pages doi: 10.1155/2013/146704. 29. M.J. Ablowitz and P.A. Clarkson, Soliton, nonlinear evolution equations and inverse scattering, Cambridge University Press, New York, 1991. 30. H. Naher and F.A. Abdullah, AIP Advances 3, 032116 (2013) doi: 10. 1063/1.4794947. 31. J. Zhang, F. Jiang and X. Zhao, Inter. J. Computer Math., 87(8) (2010) 1716. Appendix A: Zhang et al. solutions [31] Zhang et al. [31] established exact solutions of the well-known the ZK-BBM equation by using the improved )/( GG′ -expansion method which are as follows: When ,042 >− µλ 2 1 2 2 2 1 2 2 2 2 2 1 2 2 2 1 2 2 2 2 1 2 1 6bV u 1 1 C sinh 4 C cosh 4 1 2 2a( ( ) ( 4 )( )) 1 12 2 C cosh 4 C sinh 4 2 2 6bV 1 1 C sinh 4 C cosh 4 1 2 2a( ( ) ( 4 )( )) 1 12 2 C cosh 4 C sinh 4 2 2 bV 8bV V 1 , 2a − µ = − λ − µξ+ λ − µξλ − + λ − µ λ − µξ + λ − µξ − µλ − λ − µξ + λ − µξλ − + λ − µ λ − µξ+ λ − µξ λ + µ − − (A.1) where 21 ,CC are arbitrary constants. When ,042 <− µλ 2 1 2 2 2 1 2 2 2 2 2 1 2 2 2 1 2 2 2 2 1 2 2 6bV u 1 1 C sin 4 C cos 4 1 2 2a( ( ) ( 4 )( )) 1 12 2 C cos 4 C sin 4 2 2 6bV 1 1 C sin 4 C cos 4 1 2 2a( ( ) ( 4 )( )) 1 12 2 C cos 4 C sin 4 2 2 bV 8bV V 1 , 2a − µ = − − µ −λ ξ + µ − λ ξλ − + µ −λ µ − λ ξ + µ − λ ξ − µλ − − µ − λ ξ + µ − λ ξλ − + µ − λ µ −λ ξ + µ −λ ξ λ + µ − − (A.2) where 21 ,CC are arbitrary constants. Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.67 (Online Publication: Dec., 2013) When ,042 =− µλ 2 1 22 2 1 2 1 2 2 2 6bV 6bV u C C a( ( ) ( )) a( ( ) a( ( ) ( )) 2 C C 2 2 C C bV 8bV V 1 , 2a − µ − µλ = − − λ λ λ − + − + − + + ξ + ξ λ + µ − − (A.3) where 21 ,CC are arbitrary constants. When ,042 >− µλ 2 2 2 2 1 2 2 2 2 2 1 2 1 1 1 C sinh 4 C cosh 4 3bV( 4 ) 2 2u ( )) 1 12a C cosh 4 C sinh 4 2 2 bV 8bV V 1 , 2a λ − µξ + λ − µξ− λ − µ = λ − µξ + λ − µξ λ + µ − − − (A.4) where 21 ,CC are arbitrary constants. For ,01 >C 2 2 2 1 CC < above, then the solutions (A.4) turns into 22 2 2 2 01 43bV( 4 ) bV 4bV V 1 u sech ( ) , 2a 2 2a λ − µξ− λ − µ λ − µ − − = + ξ − ),(tanh 2 11 0 C C−=ξ When ,042 <− µλ 2 2 2 2 1 2 2 2 2 2 1 2 2 1 1 C sin 4 C cos 4 3bV( 4 ) 2 2u ( )) 1 12a C cos 4 C sin 4 2 2 2bV 8bV V 1 , 2a − µ −λ ξ + µ − λ ξλ − µ = µ − λ ξ + µ − λ ξ λ − µ + + + (A.5) where 21 ,CC are arbitrary constants. When ,042 =− µλ 2 2 2 2 2 1 2 2 6bVC 2bV 8bV V 1 u , 2aa(C C ) λ − µ + + = + + ξ (A.6) where 21 ,CC are arbitrary constants. Appendix B: Akbar et al. [17] Akbar et al. [17] established a generalized and improved )/( GG′ -expansion method and studied ZK-BBM equation, and obtained following solutions: When ,042 >− µλ Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.68 (Online Publication: Dec., 2013) 2 2 3 2 1 2 2 2 2 2 2 2 2 2 2 2 2 1 6bV{ d( d d 2 d 2d 2 )} u 1 1 Bsinh 4 Acosh 4 1 2 2a(d ( 4 )( )) 1 12 2 Bcosh 4 Asinh 4 2 2 6bV{ d( 2d 2 d 2 )} 1 1 Bsinh 4 Acosh 4 1 2 2a(d ( 4 )( 1 12 2 Bcosh 4 Asinh 2 2 − µ + λ + − λ + µ − λµ = − λ − µξ + λ − µξλ − + λ − µ λ − µξ + λ − µξ − µλ − λ + − λ + µ λ − µξ + λ − µξλ − + λ − µ λ − µξ+ 2 2 )) 4 {(bV 8bV V 1) 12bVd(d ) , 2a − λ − µξ λ + µ − − + −λ (B.1) where BA, are arbitrary constants. When ,042 <− µλ 2 2 3 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 6bV{ d( d d 2 d 2d 2 )} u 1 1 Bsinh 4 Acosh 4 1 2 2a(d ( 4 )( )) 1 12 2 Bcosh 4 Asinh 4 2 2 6bV{ d( 2d 2 d 2 )} 1 1 Bsinh 4 Acosh 4 1 2 2a(d ( 4 )( 1 12 2 Bcosh 4 Asinh 2 − µ + λ + − λ + µ − λµ = − − µ −λ ξ + µ − λ ξλ − + µ − λ µ − λ ξ + µ −λ ξ µλ − λ + − λ + µ − µ − λ ξ + µ −λ ξλ − + µ −λ µ −λ ξ + 2 2 )) 4 2 {(bV 8bV V 1) 12bVd(d ) , 2a − µ − λ ξ λ + µ − − + −λ (B.2) where BA, are arbitrary constants. When ,042 =− µλ 2 2 3 2 1 2 2 3 6bV{ d( d d 2 d 2d 2 )} u B a(d ( )) 2 A B {(bV 8bV V 1) 12bVd(d ) , 2a − µ + λ + − λ + µ − λµ = − λ − + + ξ λ + µ − − + −λ (B.3) where BA, are arbitrary constants. When ,042 >− µλ 2 2 2 2 2 2 2 2 1 1 1 Bsinh ( 4 ) Acosh ( 4 ) 3bV( 4 ) 2 2u ( )) 1 12a Bcosh ( 4 ) Asinh ( 4 ) 2 2 2bV 8bV V 1 , 2a λ − µξ + λ − µξλ − µ = − λ − µξ + λ − µξ λ − µ + + − (B.4) where BA, are arbitrary constants. Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.69 (Online Publication: Dec., 2013) If ,0>B 22 BA < above, then the solutions (B.4) turns into 22 2 2 2 01 43bV( 4 ) bV 4bV V 1 u sech ( ) , 2a 2 2a λ − µξλ − µ λ − µ − − = + ξ − ),(tanh 1 0 B A−=ξ When ,042 <− µλ , 2 182 )) 4 2 1 sin4 2 1 cos 4 2 1 cos4 2 1 sin ( 2 )4(3 2 2 22 22 2 22 a VbVbV AB AB a bV u ++− + −+− −+−−− −= µλ ξλµξλµ ξλµξλµλµ (B.5) where BA, are arbitrary constants. When ,042 =− µλ 2 2 2 22 6bVB 2bV 8bV V 1 u , 2aa(A B ) λ − µ + + = − + + ξ (B.6) where BA, are arbitrary constants. When ,042 >− µλ 2 2 3 2 2 2 2 2 2 2 2 2 2 2 2 2 1 3bV( 4 ) u 1 1 Bsinh 4 Acosh 4 1 2 28a(d ( 4 )( )) 1 12 2 Bcosh 4 Asinh 4 2 2 1 1 Bsinh 4 Acosh 4 6bV 1 2 2(d ( 4 )( )) 1 1a 2 2 Bcosh 4 Asinh 4 2 2 (2bV 8bV V V 1) , 2a − λ − µ = λ − µξ + λ − µξλ − + λ − µ λ − µξ + λ − µξ λ − µξ + λ − µξλ − − + λ − µ λ − µξ + λ − µξ λ − µ + + − (B.7) where BA, are arbitrary constants. When ,042 <− µλ 2 2 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3bV( 4 ) u 1 1 Bsin 4 Acos 4 1 2 28a(d ( 4 )( )) 1 12 2 Bcos ( 4 ) Asin ( 4 ) 2 2 1 1 Bsin ( 4 ) Acos ( 4 ) 6bV 1 2 2(d ( 4 )( )) 1 1a 2 2 Bcos ( 4 ) Asin ( 4 ) 2 2 (2bV 8bV V V 1) , 2a λ − µ = − − µ − λ ξ + µ − λ ξλ − + µ −λ µ − λ ξ + µ − λ ξ − µ −λ ξ + µ −λ ξλ − − + µ −λ µ − λ ξ + µ − λ ξ λ − µ + + − (B.8) Md. Nur Alam and M. Ali Akbar/ BIBECHANA 10 (2014) 58-70 : BMHSS, p.70 (Online Publication: Dec., 2013) where BA, are arbitrary constants. When ,042 =− µλ 2 2 2 3 2 2 3 3bV( 4 ) 6bV B u (d ( )) B a 2 A B 8a(d ( )) 2 A B (V 1 2bV 8bV V) , 2a − λ − µ λ = − − + λ + ξ− + + ξ + + λ − µ + (B.9) where BA, are arbitrary constants.