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Hindawi Publishing Corporation Mathematical Problems in Engineering Volume 2012, Article ID 320163, 10 pages doi:10.1155/2012/320163 Research Article Periodic Loop Solutions and Their Limit Forms for the Kudryashov-Sinelshchikov Equation Bin He, 1 Qing Meng, 2 Jinhua Zhang, 1 and Yao Long 1 1 College of Mathematics, Honghe University, Mengzi, Yunnan 661100, China 2 Department of Physics, Honghe University, Mengzi, Yunnan 661100, China Correspondence should be addressed to Bin He, [email protected] Received 5 December 2011; Revised 24 January 2012; Accepted 30 January 2012 Academic Editor: Stefano Lenci Copyright q 2012 Bin He 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 Kudryashov-Sinelshchikov equation is studied by using the bifurcation method of dynamical systems and the method of phase portraits analysis. We show that the limit forms of periodic loop solutions contain loop soliton solutions, smooth periodic wave solutions, and periodic cusp wave solutions. Also, some new exact travelling wave solutions are presented through some special phase orbits. 1. Introduction A mixture of liquid and gas bubbles of the same size may be considered as an example of a classic nonlinear medium. In practice, analysis of propagation of the pressure waves in a liquid with gas bubbles is important problem. We know that there are solitary and periodic waves in a mixture of a liquid and gas bubbles and these waves can be described by nonlinear partial dierential equations. As for examples of nonlinear dierential equations to describe the pressure waves in bubbly liquids, we can point out the Burgers equation, the Korteweg-de Vries equation, the Burgers-Korteweg-de Vries equation, and so on 1. In 2010, Kudryashov and Sinelshchikov 1 obtained a more common nonlinear partial dierential equation for describing the pressure waves in a mixture liquid and gas bubbles taking into consideration the viscosity of liquid and the heat transfer, and the equation reads as follows: u t αuu x u xxx uu xx x βu x u xx 0, 1.1 where u is a density and which model heat transfer and viscosity, α, β are real parameters. Equation 1.1 is called Kudryashov-Sinelshchikov equation, it is generalization of the

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Page 1: Periodic Loop Solutions and Their Limit Forms for the Kudryashov

Hindawi Publishing CorporationMathematical Problems in EngineeringVolume 2012, Article ID 320163, 10 pagesdoi:10.1155/2012/320163

Research ArticlePeriodic Loop Solutions and Their Limit Forms forthe Kudryashov-Sinelshchikov Equation

Bin He,1 Qing Meng,2 Jinhua Zhang,1 and Yao Long1

1 College of Mathematics, Honghe University, Mengzi, Yunnan 661100, China2 Department of Physics, Honghe University, Mengzi, Yunnan 661100, China

Correspondence should be addressed to Bin He, [email protected]

Received 5 December 2011; Revised 24 January 2012; Accepted 30 January 2012

Academic Editor: Stefano Lenci

Copyright q 2012 Bin He et al. This is an open access article distributed under the CreativeCommons Attribution License, which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.

The Kudryashov-Sinelshchikov equation is studied by using the bifurcation method of dynamicalsystems and the method of phase portraits analysis. We show that the limit forms of periodic loopsolutions contain loop soliton solutions, smooth periodic wave solutions, and periodic cusp wavesolutions. Also, some new exact travelling wave solutions are presented through some specialphase orbits.

1. Introduction

A mixture of liquid and gas bubbles of the same size may be considered as an example ofa classic nonlinear medium. In practice, analysis of propagation of the pressure waves in aliquid with gas bubbles is important problem. We know that there are solitary and periodicwaves in a mixture of a liquid and gas bubbles and these waves can be described by nonlinearpartial differential equations. As for examples of nonlinear differential equations to describethe pressure waves in bubbly liquids, we can point out the Burgers equation, the Korteweg-deVries equation, the Burgers-Korteweg-de Vries equation, and so on [1].

In 2010, Kudryashov and Sinelshchikov [1] obtained amore common nonlinear partialdifferential equation for describing the pressure waves in a mixture liquid and gas bubblestaking into consideration the viscosity of liquid and the heat transfer, and the equation readsas follows:

ut + αuux + uxxx − (uuxx)x − βuxuxx = 0, (1.1)

where u is a density and which model heat transfer and viscosity, α, β are real parameters.Equation (1.1) is called Kudryashov-Sinelshchikov equation, it is generalization of the

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2 Mathematical Problems in Engineering

KdV and the BKdV equation and similar but not identical to the Camassa-Holm equation.Undistortedwaves are governed by a corresponding ordinary differential equationwhich, forspecial values of some integration constant, is solved analytically in [1]. Ryabov [2] obtainedsome exact solutions for β = −3 and β = −4 using a modification of the truncated expansionmethod. Solutions are derived in amore straightforwardmanner and cast into a simpler form,and some new types of solutions which contain solitary wave and periodic wave solutionsare presented in [3].

In this paper, we focus on the case β = 2 of (1.1) using the bifurcation theory and themethod of phase portraits analysis [4–6], we will investigate periodic loop solutions and theirlimit forms and give some new exact travelling wave solutions.

2. Preliminary

In this paper, we always consider the case β = 2, so from now on we assume β = 2 in (1.1)without mentioning it further.

Substituting u(x, t) = 1 − φ(x + αt) = 1 − φ(ξ) into (1.1) and integrating the resultingequation once with respect to ξ, we obtain

g − 2αφ +α

2φ2 − φφ′′ − (φ′)2 = 0, (2.1)

where g is the integral constant.Letting y = dφ/dξ, we get the following planar system:

dξ= y,

dy

dξ=g − 2αφ + (α/2)φ2 − y2

φ. (2.2)

Using the transformation dξ = φdτ , it carries (2.2) into the Hamiltonian system:

dτ= φy,

dy

dτ= g − 2αφ +

α

2φ2 − y2. (2.3)

Since both system (2.2) and (2.3) have the same first integral:

φ2(y2 − g +

43αφ − 1

4αφ2)

= h, (2.4)

then the two systems above have the same topological phase portraits except the line φ = 0.Therefore, we can obtain the bifurcation phase portraits of system (2.2) from that of system(2.3).

Write Δ = 2α(2α − g). Clearly, when Δ > 0, system (2.3) has two equilibrium pointsat (φ1,2, 0) in φ-axis, where φ1,2 = (2α ±

√Δ)/α. When Δ = 0, system (2.3) has only one

equilibrium point at (2, 0) in φ-axis. When Δ < 0, system (2.3) has no any equilibrium pointin φ-axis. When g > 0, there exist two equilibrium points of system (2.3) in line φ = 0 at(0,±√g).

LetM(φe, ye) be the coefficient matrix of the linearized system of (2.3) at equilibriumpoint (φe, ye), J = det(M(φe, ye)), and T = trace(M(φe, ye)). By the theory of planar

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Mathematical Problems in Engineering 3

dynamical systems, we know that for an equilibrium point (φe, ye) of a planar integrablesystem, (φe, ye) is a saddle point if J < 0, a center point if J > 0 and T = 0, a cusp if J = 0and the Poincare index of (φe, ye) is zero. By using the properties of equilibrium points andbifurcation method of dynamical systems, we can show that the bifurcation phase portraitsof systems (2.2) and (2.3) is as drawn in Figure 1.

From Figures 1(b), 1(c), 1(d), 1(e), and 1(l), we have the following results.

3. Main Results

Proposition 3.1. (i)When α < 0, g = 2α, for h = (−4/3)α defined by (2.4), (1.1) has a loop-solitonsolution.

(ii) When α < 0, g = 2α, for h ∈ (0, (−4/3)α), there exists a family of uncountably infinitemany periodic loop solutions of (1.1). Moreover, the periodic loop solutions converge to the loop-solitonsolution as h approaches (−4/3)α.

(iii) When α < 0, g = 2α, for h ∈ ((−4/3)α,+∞), there exists a family of uncountablyinfinite many periodic loop solutions of (1.1). Moreover, the periodic loop solutions converge to theloop-soliton solution as h approaches (−4/3)α.

Proposition 3.2. Denote that h1 = H(φ1, 0) and h2 = H(φ2, 0).(i) When α < 0, 2α < g < 0, for h = h1 defined by (2.4), (1.1) has a loop-soliton solution and

has a solitary wave solution.(ii) When α < 0, 2α < g < 0, for h ∈ (h2, h1), there exist a family of uncountably infinite

many periodic loop solutions and a family of uncountably infinite many smooth periodic wave solutionsof (1.1). Moreover, the periodic loop solutions converge to the loop-soliton solution and the smoothperiodic wave solutions converge to the solitary wave solution as h approaches h1.

(iii) When α < 0, 2α < g < 0, for h ∈ (h1,+∞), there exists a family of uncountably infinitemany periodic loop solutions of (1.1). Moreover, the periodic loop solutions converge to the loop-solitonsolution as h approaches h1.

(iv) When α < 0, 2α < g < 0, for h ∈ (0, h2], there exists a family of uncountably infinitemany periodic loop solutions of (1.1).

Proposition 3.3. (i) When α < 0, g = 0, for h = 0 defined by (2.4), (1.1) has a smooth periodicwave solution.

(ii) When α < 0, g = 0, for h ∈ (0,+∞), there exists a family of uncountably infinite manyperiodic loop solutions of (1.1). Moreover, the periodic loop solutions converge to the smooth periodicwave solution as h approaches 0.

Proposition 3.4. (i) When α < 0, g > 0, for h = 0 defined by (2.4), (1.1) has two cusp periodicwave solutions.

(ii) When α < 0, g > 0, for h ∈ (0,+∞), there exists a family of uncountably infinite manyperiodic loop solutions of (1.1). Moreover, the periodic loop solutions converge to the cusp periodicwave solutions as h approaches 0.

Proposition 3.5. Denote that h2 = H(φ2, 0).(i)When α > 0, g < 0, for h = h2 defined by (2.4), (1.1) has a loop-soliton solution.(ii) When α > 0, g < 0, for h ∈ (0, h2), there exists a family of uncountably infinite many

periodic loop solutions of (1.1). Moreover, the periodic loop solutions converge to the loop-solitonsolution as h approaches h2.

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4 Mathematical Problems in Engineering

y y

2

y

2φ φ φ

y

5

y

5

y

φ φ φ

y

y

y

y

y

φ

y

φ

) α < 0, g < 2α ) α < 0, g = 2α ) α < 0, 2α < g < 0

) α < 0, g = 0 ) α < 0, g > 0 ) α > 0, g > 2α

) α > 0, g = 2α ) α > 0, (16/9) (16/9)

(16/9)

α < g < 2α ) α > 0, g =

) α > 0, 0 < g < ) α > 0, g = 0 ) α > 0, g < 0

(a (b (c

(d (e (f

(g (h ( i

(j (k ( l

α

α

Figure 1: The bifurcation phase portraits of systems (2.2) and (2.3).

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Mathematical Problems in Engineering 5

4. Exact Traveling Wave Solutions ofthe Kudryashov-Sinelshchikov Equation

Corresponding to Figure 1(b), the graph defined by H(φ, y) = (−4/3)α consist of twohyperbolic sectors of the cusp (2, 0) and an open-end curve Γ0 passing through the point(−2/3, 0). It follows from (2.4) that

y = ±(2 − φ)

√−α(2 − φ)(φ + 2/3

)

2φ, −2

3≤ φ < 2, φ /= 0. (4.1)

Substituting (4.1) into the dφ/dξ = y and integrating along the curve Γ0 and noting thatu(x, t) = 1 − φ(x + αt) = 1 − φ(ξ), we obtain the following representation of loop-solitonsolution:

u(χ)= 1 − 2sin2(χ

)+23cos2

(χ),

ξ(χ)=

4√−α

(34tan(χ) − χ

),

(4.2)

where χ is a new parametric variable.Corresponding to Figure 1(c), the graph defined by H(φ, y) = H(φ1, 0) consists of an

open-end curve Γ1 passing through the point (φm, 0) and a homoclinic orbit connecting with

saddle point (φ1, 0) and passing point (φM, 0), where φm = (3√Δ− 2α− 2

√2α(2α − 3

√Δ))/−

3α, φM = (3√Δ − 2α + 2

√2α(2α − 3

√Δ))/ − 3α. It follows from (2.4) that

y = ±(φ1 − φ

)√−α(φM − φ)(φ − φm)

2φ, φm ≤ φ < φ1, φ /= 0, (4.3)

y = ±(φ − φ1

)√−α(φM − φ)(φ − φm)

2φ, φ1 ≤ φ ≤ φM. (4.4)

Substituting (4.3) into the dφ/dξ = y and integrating along the curve Γ1, we can obtain thefollowing representation of loop-soliton solution:

u(χ)= 1 −

φ1

[φMsinh2(ωχ

) − φmcosh2(ωχ)]

+ φmφM[φMcosh2(ωχ

) − φmsinh2(ωχ)] − φ1

,

ξ(χ)=

2√−α

⎝χ − 2 arctan

√φ1 − φmφM − φ1

tanh(ωχ)⎞

⎠,

(4.5)

where ω =√(φ1 − φm)(φM − φ1)/2φ1.

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6 Mathematical Problems in Engineering

Substituting (4.4) into the dφ/dξ = y and integrating along the homoclinic orbit, wecan obtain the following representation of solitary wave solution:

u(χ)= 1 −

φ1

[φMcosh2(ωχ

) − φmsinh2(ωχ)] − φmφM

[φMsinh2(ωχ

) − φmcosh2(ωχ)]

+ φ1

,

ξ(χ)=

2√−α

⎝χ − 2 arctan

√φM − φ1

φ1 − φm tanh(ωχ)⎞

⎠,

(4.6)

where ω =√(φ1 − φm)(φM − φ1)/2φ1.

Moreover, the graph defined byH(φ, y) = h, h ∈ (H(φ2, 0),H(φ1, 0)), consists of twoopen-end curves Γ2,Γ3, and a periodic orbit, say Ψ, enclosing the center point (φ2, 0). Thecurve Ψ passes through the points (γ1, 0) and (γ2, 0), while Γ2,Γ3 pass through the points(γ3, 0) and (γ4, 0), respectively, where γ1, γ2, γ3, γ4(γ4 < 0 < γ3 < γ2 < γ1) are four real roots ofψ4 − (16/3)ψ3 + (4g/α)ψ2 + (4h/α) = 0. It follows from (2.4) that

y = ±

√−α(γ1 − φ

)(γ2 − φ

)(γ3 − φ

)(φ − γ4

)

2φ, γ4 ≤ φ ≤ γ3, φ /= 0, (4.7)

y = ±

√−α(γ1 − φ

)(φ − γ2

)(φ − γ3

)(φ − γ4

)

2φ, γ2 ≤ φ ≤ γ1. (4.8)

Let us denote by F(·, k) andΠ(·, ·, k) the Legendre’s incomplete elliptic integrals of thefirst and third kinds, respectively, with the modulus k (see [7]).

Substituting (4.7) into the dφ/dξ = y and integrating along the curve Γ2, we can obtainthe implicit representation of periodic loop solution for u ∈ [1 − γ3, 1 − γ4]:

4γ3

α21

√−α(γ1 − γ3

)(γ2 − γ4

)

×⎡

⎣(α21−α22

⎝arcsin

√√√√(γ2−γ4

)(γ3+u−1

)

(γ3−γ4

)(γ2+u −1)

⎠, α21, k

+α22F

⎝arcsin

√√√√(γ2−γ4

)(γ3+u−1

)

(γ3−γ4

)(γ2+u−1

)

⎠, k

⎦ = ±ξ,

(4.9)

where α21 = (γ3 − γ4)/(γ2 − γ4), α22 = γ2(γ3 − γ4)/γ3(γ2 − γ4), k =√(γ1 − γ2)(γ3 − γ4)/(γ1 − γ3)(γ2 − γ4).

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Mathematical Problems in Engineering 7

Substituting (4.8) into the dφ/dξ = y and integrating along the periodic orbit, we canobtain the implicit representation of smooth periodic wave solution for u ∈ [1 − γ1, 1 − γ2]:

4γ2

α21

√−α(γ1 − γ3

)(γ2 − γ4

)

×⎡

⎣(α21 − α22

⎝arcsin

√√√√(γ1 − γ3

)(1 − u − γ2

)

(γ1 − γ2

)(1 − u − γ3

)

⎠, α21, k

+α22F

⎝arcsin

√√√√(γ1 − γ3

)(1 − u − γ2

)

(γ1 − γ2

)(1 − u − γ3

)

⎠, k

⎦ = ±ξ,

(4.10)

where α21 = (γ1 − γ2)/(γ1 − γ3), α22 = γ3(γ1 − γ2)/γ2(γ1 − γ3), k =√(γ1 − γ2)(γ3 − γ4)/(γ1 − γ3)(γ2 − γ4).

Corresponding to Figure 1(d), the graph defined by H(φ, y) = 0 is a periodicorbit enclosing the center point (2(α −

√α(α − 1))/α, 0) and passing through the points

(0, 0), (16/3, 0). It follows from (2.4) that

y = ±12

−αφ(163

− φ), 0 ≤ φ ≤ 16

3. (4.11)

Substituting (4.11) into the dφ/dξ = y and integrating along the periodic orbit, we can obtainthe following representation of smooth periodic wave solution:

u(x, t) = 1 − 163cos2(ω(x + αt)), (4.12)

where ω = (1/4)√−α.

Corresponding to Figure 1(e), the graph defined by H(φ, y) = 0 consists of fourheteroclinic orbits: two of them connecting the saddle points (0,±√g) with (φm, 0), and theothers connecting saddle points (0,±√g)with (φM, 0), where φm = 2(4α+

√α(16α − 9g))/3α,

φM = 2(4α −√α(16α − 9g))/3α. It follows from (2.4) that

y = ±12

√−α(φ − φm

)(φM − φ), φm ≤ φ ≤ 0, (4.13)

y = ±12

√−α(φ − φm

)(φM − φ), 0 ≤ φ ≤ φM. (4.14)

Substituting (4.13) into the dφ/dξ = y and integrating along the heteroclinic orbit, we canobtain the following representation of cusp periodic wave solution:

u(x, t) = 1 − φMsin2(Ω −ω|x + αt − 2nT |) − φmcos2(Ω −ω|x + αt − 2nT |), (4.15)

whereω = (1/4)√−α,Ω = arctan(

√−φm/φM), T = 2|Ω|, n = 0,±1,±2, . . . , (2n−1)T ≤ x+αt ≤(2n + 1)T .

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8 Mathematical Problems in Engineering

Substituting (4.14) into the dφ/dξ = y and integrating along the heteroclinic orbit, wecan obtain the following representation of cusp periodic wave solution:

u(x, t) = 1 − φMcos2(Ω −ω|x + αt − 2nT |) − φmsin2(Ω −ω|x + αt − 2nT |), (4.16)

where ω = (1/4)√−α, Ω = arctan(

√−φM/φm), T = 2|Ω|, n = 0,±1,±2, . . ., (2n − 1)T ≤ x + αt ≤(2n + 1)T .

Moreover, the graph defined by H(φ, y) = h, h ∈ (0,+∞) consists of two open-endcurves Γ4,Γ5 passing through the points (φm, 0) and (φM, 0), respectively, where (φM −φ)(φ−φm)[(φ − b1)2 + a21] = −φ4 + (16/3)φ3 − (4g/α)φ2 − 4h/α. It follows from (2.4) that

y = ±

√−α(φM − φ)(φ − φm

)[(φ − b1

)2 + a21]

2φ, φm ≤ φ ≤ φM, φ /= 0.

(4.17)

Substituting (4.17) into the dφ/dξ = y and integrating along the curve Γ4, we can obtain theimplicit representation of periodic loop solution for u ∈ [1 − φM, 1 − φm]:

2(φmA + φMB

)

(A − B)√AB

{

α2F(ϕ, k)+α1 − α21 − α21

[

Π

(

ϕ,α21

α21 − 1, k

)

− α1f1]

− η0}

= ±ξ, (4.18)

whereA =√(φM − b1)2 + a21, B =

√(φm − b1)2 + a21, α1 = (A−B)/(A+B), α2 = (φmA−φMB)/

(φmA+φMB), k =√((φM − φm)2 − (A − B)2)/4AB, k1 =

√1 − k2, η0 = [α22F(ϕ, k) + ((α1 −α2)/

(1 − α21))(Π(ϕ, α21/(α21 − 1), k) − α1f1)]|u=1−φM , ϕ = arccos(((φM + u −

1)B + (φm + u − 1)A)/((φM + u − 1)B − (φm + u − 1)A)), f1 =√(1 − α21)/(k2 + k21α21) arctan(

√(sin2ϕ(k2 + k21α

21))/(1 − k2sin2ϕ)(1 − α21)).

Corresponding to Figure 1(l), the graph defined byH(φ, y) = H(φ2, 0) consists of twohyperbolic sectors of the saddle point (φ2, 0) and two open-end curves Γ6,Γ7 passing through

the points (φm, 0), (φM, 0), respectively, where φm = (2α+3√Δ−2

√2α(2α + 3

√Δ))/3α, φM =

(2α + 3√Δ + 2

√2α(2α + 3

√Δ))/3α. It follows from (2.4) that

y = ±(φ − φ2

)√α(φm − φ)(φM − φ)

2φ, φ2 < φ ≤ φm, φ /= 0. (4.19)

Substituting (4.19) into the dφ/dξ = y and integrating along the curve Γ6, we can obtain thefollowing representation of loop-soliton solution:

u(χ)= 1 −

φ2

[φMsinh2(ωχ

) − φmcosh2(ωχ)]

+ φmφM[φMcosh2(ωχ

) − φmsinh2(ωχ)] − φ2

,

ξ(χ)=

2√α

⎝χ − 2 tan h−1⎛

√φm − φ2

φM − φ2tanh

(ωχ)⎞

⎠,

(4.20)

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Mathematical Problems in Engineering 9

where ω =√(φm − φ2)(φM − φ2)/2φ2, tan h

−1(·) is the inverse function of the hyperbolicfunction tanh(·), see [7].

Moreover, the graph defined by H(φ, y) = h, h ∈ (0,H(φ2, 0)) consist of fouropen-end curves Γ8, Γ9, Γ10 and Γ11 passing through the points (γ4, 0), (γ3, 0), (γ2, 0), (γ1, 0)respectively, where γ1, γ2, γ3, γ4 (γ4 < γ3 < 0 < γ2 < γ1) are four real roots of ψ4 − (16/3)ψ3 +(4g/α)ψ2 + (4h/α) = 0. It follows from (2.4) that

y = ±

√α(γ1 − φ

)(γ2 − φ

)(φ − γ3

)(φ − γ4

)

2φ, γ3 ≤ φ ≤ γ2, φ /= 0. (4.21)

Substituting (4.21) into dφ/dξ = y and integrating along the curve Γ10, we can obtain theimplicit representation of periodic loop solution for u ∈ [1 − γ2, 1 − γ3]:

4γ2

α21

√α(γ1 − γ3

)(γ2 − γ4

)

×⎡

⎣(α21 − α22

⎝arcsin

√√√√(γ1 − γ3

)(γ2 + u − 1

)

(γ2 − γ3

)(γ1 + u − 1

)

⎠, α21, k

+α22F

⎝arcsin

√√√√(γ1 − γ3

)(γ2 + u − 1

)

(γ2 − γ3

)(γ1 + u − 1

)

⎠, k

⎦ = ±ξ,

(4.22)

where α21 = (γ2 − γ3)/(γ1 − γ3), α22 = γ1(γ2 − γ3)/γ2(γ1 − γ3), k =√(γ2 − γ3)(γ1 − γ4)/(γ1 − γ3)(γ2 − γ4).

Remark 4.1. Denote that (i) α < 0, g = 2α, h ∈ (0, (−4/3)α), (ii)α < 0, g = 2α, h ∈((−4/3)α,+∞), (iii)α < 0, 2α < g < 0, h ∈ (0,H(φ2, 0)], (iv)α < 0, 2α < g < 0, h ∈(H(φ1, 0),+∞), (v)α < 0, g = 0, h ∈ (0,+∞), we can obtain the implicit representation ofperiodic loop solution similar to (4.18) when β, α, g, and h satisfy one and only one of aboveconditions, we omit it for brevity.

Example 4.2. Taking α = −1, g = 1 and h = 1, we get the approximations ofA,B, φm, φM, a1, b1, α1, α2, k, k1 in the formula (4.18), where A

.= 5.846662930, B.=

1.525667184, φm.= −1.117067993, φM .= 6.016534182, a1

.= 0.7403378831, b1.= 0.2169335722,

α1.= 0.586109911, α2

.= −5.932667554, k .= 0.9502338139, k1.= 0.3115376364.

5. Conclusion

In this paper, using the bifurcation theory and the method of phase portraits analysis, weinvestigated periodic loop solutions and their limit forms of the Kudryashov-Sinelshchikovequation and show that the limit forms contain loop soliton solutions, smooth periodicwave solutions, and periodic cusp wave solutions. We also obtain the exact parametricrepresentations above travelling wave solutions. The results of this paper have enrichedresults of [1–3]. We would like to study the Kudryashov-Sinelshchikov equation further.

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10 Mathematical Problems in Engineering

Acknowledgments

The authors thank the referees for some perceptive comments and for some valuablesuggestions. This work is supported by the National Natural Science Foundation of China(no. 11161020).

References

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[2] P. N. Ryabov, “Exact solutions of the Kudryashov-Sinelshchikov equation,” Applied Mathematics andComputation, vol. 217, no. 7, pp. 3585–3590, 2010.

[3] M. Randruut, “On the Kudryashov-Sinelshchikov equation for waves in bubbly liquids,” PhysicsLetters, Section A, vol. 375, no. 42, pp. 3687–3692, 2011.

[4] L. Zhang and J. Li, “Dynamical behavior of loop solutions for the (2, 2) equation,” Physics Letters A,vol. 375, no. 33, pp. 2965–2968, 2011.

[5] J. Li, Y. Zhang, and G. Chen, “Exact solutions and their dynamics of traveling waves in threetypical nonlinear wave equations,” International Journal of Bifurcation and Chaos in Applied Sciences andEngineering, vol. 19, no. 7, pp. 2249–2266, 2009.

[6] B. He, “Bifurcations and exact bounded travelling wave solutions for a partial differential equation,”Nonlinear Analysis: Real World Applications, vol. 11, no. 1, pp. 364–371, 2010.

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Page 11: Periodic Loop Solutions and Their Limit Forms for the Kudryashov

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