Exact Solutions For Non Linear Partial Differential Equations Using Hyperbolic-sine Function Method M.F. El-Sabbagh, R. Zait And R.M. Abdelazeem Mathematics Department, Faculty of science, Minia university, Egpt Corresponding e-mail: rasha_math24@yahoo.com Abstract In this paper, we establish exact solutions for some nonlinear partial differential equations. The Hyperbolic-sine method (ref. [1]) is used to construct periodic and solitary wave solutions for some soliton equations and systems such as the Klien-Gordon, the Kadomtsev-Petviashvili, and the Zakharov-Kuznetsov (ZK) equations, the generalized coupled Drinfeld – sokolov –wilso, and the general coupled Hirota-Satsuma Kdv systems. Keywords: Nonlinear PDEs and systems, Exact Solutions, Nonlinear Waves and Hyperbolic-sine function method. 1. Introduction The aim of the present paper is to extend the cosine-function method introduced to find new solitary solutions to the some soliton equations such as the Klien-Gordon, the Kadomtsev-Petviashvili, and the ZakharovKuznetsov (ZK) equations, the generalized coupled Drinfeld –sokolov – wilso, and the general coupled Hirota-Satsuma Kdv systems. 2. Hyperbolic-sine function method (ref. [1]) Consider the nonlinear partial differential equation in the form πΉ(π’π‘ , π’π₯ , π’π π’π₯ , π’π₯π₯π₯ , π’π₯π₯π‘ , … … … . ) (1) where π’(π₯,π‘) is the solution of (1); and π’π‘ , π’π₯ etc, are the partial derivatives of π’ with respect to t and x, respectively. We assume that equation (1) admits travelling wave solution. We use the transformation π’(π₯, π‘) = π(π), π = π₯ − ππ‘ − π (2) Where c is the speed of the travelling wave and π is a constant. This enables us to use the following 1 π ππ‘ π (·)=−cππ (·), π ππ₯ π π2 π2 (·)=ππ (·), ππ₯ 2 (·)=ππ2 (·),…….. (3) Using the above transformation the nonlinear partial differential equation (1) is transformed to nonlinear ordinary differential equation: ππ πΊ( , ππ n ππ π3 π π ππ , 3 , … … . . ) = 0 ππ (4) By integrating equation (4) with respect to π, we obtain π» (π, π n+1 2 , π π 2 ,……..) ππ =0 (5) The solution of equation (2) can be expressed as π’(π₯, π‘) = π(π)=ππ ππβπ½ (ππ) (6) Where π, π½ and π are unknown parameters which will be determined. Then we have ππ = −π π½ ππ ππβπ½−1 (ππ) csch(ππ) ππ π2 π ππ 2 = π π2 π½(π½ − 1)π ππβπ½−2 (ππ)+ π π2 π½(π½ − 1)π ππβπ½ (ππ) +π π2 π½ π ππβπ½ (ππ) (7) We substitute (6) and (7) in (4) to obtain an equation in different powers of sine-hyperbolic functions. Now equating the coefficients of the same powers of sine-hyperbolic functions we obtain a system of algebraic equations in the parameters λ, β and μ. This system can be solved to obtain the values of λ, β and μ. The exact analytical solution of NLPDE (2) is then obtained by substituting the values of the parameters in (6). 3. Applications In order to illustrate the effectiveness of the proposed method examples of mathematical interest are chosen as follows: 2 3.1.The Klien-Gordon equation In this section we introduce solitary exact solution for a generalized Klien-Gordon equation which is as follows: π’π‘π‘ -π’π₯π₯ −π’ + π’π = 0 (8) from equations (3), we have: c2 π 2 π(π) ππ 2 π 2 π(π) − ππ 2 − π(π ) − (π(π))π = 0 (9) From equations (6) and (7) we have: (c 2 − 1)[ π π2 π½ (π½ − 1)sinhπ½−2 (ππ ) + π π2 π½ (π½ − 1)sinhπ½ (ππ ) + π π2 π½sinhπ½ (ππ )] − π sinhπ½ (ππ ) −π π sinhππ½ (ππ ) = 0 (10) By balancing the exponents of each pair of sinsh we have: (c 2 − 1)π π2 π½(π½ − 1) + (c 2 − 1)π π2 π½ − π = 0, π½− 2 1−π =0 (c 2 − 1)π π2 π½(π½ − 1) − π π =0 (11) Using MATHEMATICA package software for solving the system equation (11) we obtain: π½= 2 1−π , π=− 1 √1−2π+π2 , 2√π 2 −1 π = 21−π ( 1 1+π 1 )1−π (12) Thus we obtain a new exact solution of the general Klien-Gordon equation in the form 1 1−π π’(π₯, π‘) = 2 1 2 2 √1−2π+π 1 1−π (1+π) π πππ β1−π ((− 2√π2 −1 ) (π₯ − ππ‘)) (13) As special case if p=3 we get the Klien-Gordon equation (ref. [2]) in the following form: π’π‘π‘ -π’π₯π₯ −π’ + π’3 = 0 (14) and thus its exact soliton solution is 2 π’(π₯, π‘) = √ √−1 + π 2 π ππβ−1 ( 3 β √3 (π₯ − ππ‘)) 3 (15) 3.2. The Kadomtsev-Petviashvili (KP) equation Consider the following nonlinear partial differential equation (refs. [3], [4], [5], [6] and [7]) (π’π‘ + ππ’π π’π₯ + π’π₯π₯π₯ )π₯ + πΌπ’π¦π¦ = 0 (16) From equations (3), we have: π ππ(π) ππ(π) π 3 π(π) π 2 π(π) π + ππ(π) + =0 (−π )+πΌ ππ ππ ππ ππ 3 ππ 2 (17) By integration twice we have: (πΌ − π )π (π ) + π+1 π π+1 (π(π )) + π 2 π(π) =0 ππ 2 (18) [[[ From equations (6) and (7) we have: π π π+1 sinh(π+1)π½ (ππ) π+1 2 π½−2 (ππ) + π π π½(π½ − 1)sinhπ + π π2 π½(π½ − 1)sinhπ½ (ππ) + π π2 π½sinhπ½ (ππ) = 0 (πΌ − π)π sinhπ½ (ππ) + (19) By balancing the exponents of each pair of sinsh we have: 2 π π π+1 π½ + = 0, π π+1 + π π2 π½(π½ − 1) = 0, (πΌ − π)π + π π2 π½(π½ − 1) + π π2 π½ = 0 (20) Using MATHEMATICA package software for solving the system equation (20) we obtain: 2 π½=− , π −1 π π (πΌ−π)(π2 +3π+2) π = ± √π − πΌ, π = 2 ( 2 π 1 π ) (21) Thus we now have new exact solution of the Kadomtsev-petviashvili equation is given by −1 π π’(π₯, π‘ ) = 2 ( 1 (πΌ−π)(π2 +3π+2) π π ) π ππβ − 2 π π (± √π − πΌ(π₯ + π¦ − ππ‘ )) 2 4 (22) 3.3.The Zakharov-Kuznetsov (ZK) equation This ZK appears in many areas of physics, applied Mathematics, and Engineering. In particular, it shows up in the areas of Plasma Physics. The ZK govern the behaviour of weakly nonlinear ion-acoustics waves in a plasma comprising of cold ion and hot isothermal electron in the presence of a uniform magnetic field. The ZK equation (refs. [8], [9], [10], [11], [12] and [13]) is given by π’π‘ + ππ’π π’π₯ + π(π’π₯π₯ + π’π¦π¦ )π₯ = 0 (23), where π’(π₯, π¦, π‘) = π(π), π = π₯ + π¦ − ππ‘ (24) From equations (3), we have: ππ(π) ππ(π) π π 2 π(π) π −π + π(π(π)) + π (2 ) ππ ππ ππ ππ 2 (25) By integration we have: −π π(π) + π π 2 π(π) π+1 (π) + 2π (π ) π+1 ππ 2 (26) From equations (6) and (7) we have: −ππsinhπ½ (ππ ) + π π+1 π π+1 sinh(π+1)π½ (ππ ) + 2ππ π2 π½ (π½ − 1)sinhπ½−2 (ππ ) + 2ππ π2 π½ (π½ − 1)sinhπ½ (ππ ) + 2ππ π2 π½sinhπ½ (ππ ) = 0 (27) By balancing the exponents of each pair of sinsh we have: −ππ + 2ππ π2 π½(π½ − 1) + 2ππ π2 π½ = 0, π½+ 2 = 0, π π π π+1 + 2ππ π2 π½(π½ − 1) = 0 π+1 Using MATHEMATICA package software for solving the system equation (28) we obtain: 5 (28) −1 π = 2π( −2π−2ππ−ππ2 1 )π , π½ = π −2 π , π=± √ππ 2√2π (29) Thus we obtain new exact solution of the ZK equation in the form: π’(π₯, π‘ ) = 2 −1 π 1 −2 −2π−2ππ−ππ2 π √ππ π (± ( ) π πππ β π 2√2π (π₯ − ππ‘)) (30) 3.4. The generalized coupled Drinfeld –sokolov –wilso system This system ( refs. [14], [15], [16], [17], [18]) is given by π’π‘ − 3π£π£π₯ = 0, π£π‘ − 3π£π₯π₯π₯ − π(π’π£)π₯ = 0 (31) We assume the solution of the system (30) in the form: π’(π₯, π‘) = π(π), π£(π₯, π‘) = π(π), π = π₯ − ππ‘ (32) From equations (2) and (3), we have: −π ππ(π) ππ(π) − 3π ππ ππ = 0, −π ππ(π) π3 π(π) π − 3 3 − a ππ (π (π )π (π )) ππ ππ =0 (33) By integration we have: [[ π(π) = − 3 2π (π(π))2 , −ππ(π) − 3 π 2 π(π) ππ 2 − a(π(π)π(π)) = 0 (34) Thus from (33) and (34) we have: −ππ(π) − 3 π 2 π(π) ππ 2 − 3a 2c (π(π))3 = 0 (35), We assume π£ππ βπ¦ππππππππ π πππ πππ‘βπππ π‘βππ‘: π(π) = π sinhπ½ (ππ) (36) Thus we have −ππ sinhπ½ (ππ ) − 3[ππ2 π½ (π½ − 1)sinhπ½−2 (ππ ) + π π2 π½ (π½ − 1)sinhπ½ (ππ ) + π π2 π½sinhπ½ (ππ )] + 3π 2π π3 π½sinh3π½ (ππ ) = 0. (37) 6 By balancing the exponents of each pair of sinsh we have: −ππ − 3ππ2 π½(π½ − 1) − 3ππ2 π½ = 0, −3ππ2 π½(π½ − 1) + 3π 2π π½ + 1 = 0, π3 =0 (38) Using MATHEMATICA package software for solving the system equation (38) we obtain: π π = ±√ , π=± 3 2π √3π , π½ = −1 (39) Thus the exact solution of the generalized coupled Drinfeld –sokolov – wilso system is given as follows: π£(π₯, π‘) = ± π’(π₯, π‘) = ± 2π √3π π sinh−1 (±√ (π₯ − ππ‘)), 3 2π π sinh−2 (±√ (π₯ − ππ‘)) π 3 (40) 3.5. The general couplied Hirota-Satsuma Kdv system The general couplied Hirota-Satsuma Kdv system (refs. [18], [19], [20]) is given as follows: π’π‘ − ππ’π₯π₯π₯ − 3π’π’π₯ + 6π£π£π₯ = 0, π£π‘ + ππ£π₯π₯π₯ + 3(π’π£)π₯ = 0 (41), To obtain the travelling wave solutions we use the following transformations: π’(π₯, π‘) = π(π), π£(π₯, π‘) = π(π), π = π₯ − ππ‘ (42) From equations (2) and (3), we have: ππ(π) π 3 π(π) ππ(π) ππ(π) −π −π − 3π(π) + 6π(π) = 0, ππ ππ 3 ππ ππ ππ(π) π 3 π(π) π −π +π + 3 (π(π)π(π)) = 0 ππ ππ 3 ππ 7 (43) By integration we have π 2 π(π) 3 2 2 (π) −π π(π) − π − + 3(π(π)) = 0, (π ) ππ 2 2 π 2 π(π) −π π(π) + π + 3ππ = 0 ππ 2 (44) If we take via hyperbolic sine method the following forms: π(π) = π1 sinhπ½1 (ππ), π(π) = π2 sinhπ½2 (ππ) (45) from equation (45), equation (44) becomes in the following form: [ ππ1 sinhπ½1 (ππ) − π[π1 π2 π½1 (π½1 − 1)sinhπ½1−2 (ππ) + π1 π2 π½1 (π½1 − 1)sinhπ½1 (ππ) + π1 π2 π½1 sinhπ½1 (ππ) 3 − π1 2 sinh2π½1 (ππ)+3π2 2 sinh2π½2 (ππ) = 0, 2 −ππ2 sinhπ½2 (ππ) + π[π2 π2 π½2 (π½2 − 1)sinhπ½2−2 (ππ) + π2 π2 π½2 (π½2 − 1)sinhπ½2 (ππ) + π2 π2 π½2 sinhπ½2 (ππ) + 3π1 π2 sinhπ½1+π½2 (ππ) = 0 (46) By balancing the exponents of each pair of sinsh we have: −ππ1 − ππ1 π2 π½1 (π½1 − 1) − ππ1 π2 π½1 = 0, 2π½1 = 2π½2 = π½1 − 2, 3 −ππ1 π2 π½1 (π½1 − 1) − π1 2 +3π2 2 = 0, 2 −ππ2 + ππ2 π2 π½2 (π½2 − 1) + ππ2 π2 π½2 = 0, π½2 − 2 = π½1 + π½2 , (47) ππ2 π2 π½2 (π½2 − 1) + 3π1 π2 = 0 Using MATHEMATICA package software for solving the system equation we have π½1 = π½2 = −2, π = −π, π π 3 1 π π1 = , π2 = ± √ , π = ± √ 2 2 2 2 π 8 (48) Thus the exact solution of the general couplied Hirota-Satsuma Kdv system (41) is given as π 1 π π’(π₯, π‘) = sinh−2 (± √ (π₯ − ππ‘)), 2 2 π π 3 1 π π£(π₯, π‘) = ± √ sinh−2 (± √ (π₯ − ππ‘)) 2 2 2 π (49), where a is constant. 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