#### Abstract

The recently introduced technique, namely, the extended complex method, is used to explore exact solutions for the generalized fifth-order KdV equation. Appropriately, the rational, periodic, and elliptic function solutions are obtained by this technique. The 3D graphs explain the different physical phenomena to the exact solutions of this equation. This idea specifies that the extended complex method can acquire exact solutions of several differential equations in engineering. These results reveal that the extended complex method can be directly and easily used to solve further higher-order nonlinear partial differential equations (NLPDEs). All computer simulations are constructed by maple packages.

#### 1. Introduction

In the 20 century, nonlinear science (NLS) plays a significant role in special inventions, for example, the invention of the radio, the discovery of DNA structure for biology, the development of quantum theory for theoretical physics and chemistry, and the invention of transister for computer engineering. It is well known that NLS belongs to the NLPDEs which are introduced in several areas such as fluid thermodynamics, plasma diffusion, biology, physics, geometry, and population dynamics.

Lots of studies are focused on the differential equations [1–10], and many effective techniques are used to acquire analytical and numerical solutions for NLPDEs such as sine-cosine method [11], extended sinh-Gorden equation expansion method [12], variation iteration algorithm [13], homotopy perturbation method [14], F-expansion method [15], Exp-function expansion method [16], first integral method [17], Ansatz method [18], generalized Kudryashov method [19], -expansion method [20], projective Riccati equation method [21], tanh method [22], nonpolynomial spline method [23], B-spline method [24], B-spline collocation [25], Weierstrass elliptic function method [26], Laplace decomposition method [27], extended direct algebraic method [28, 29], Sub-ODE method [30], Darboux transformation [31], and extended tanh-coth method [32, 33]. The generalized fifth-order KdV equation [34] is represented by where , , , and are the arbitrary constants. This equation is a nonlinear model in many long wave physical phenomena. It is used in the shallow water wave with surface tension and magnetoacoustic wave in plasma. Several researchers have explored the analytical solutions of generalized fifth-order KdV equation such as Hedli and Kadem have attained a new analytical solution for the fifth-order KdV equation by the exponential expansion method [35]. Dinarvand et al. have found approximate analytical solutions of the sawada-kotera and Lax’s fifth-order KdV equations by homotopy analysis technique [36]. Salas and Lugo have introduced extended tanh method to obtain the exact solutions of the general fifth-order KdV equation [37]. Alam and Xin et al. have attained new exact solutions by -expansion method of modified KdV-Zakharov-Kuznetsov equation [38]. Ganji and Abdollahzadeh have introduced the sech method and rational exp-function method to find the exact traveling wave solutions of the Lax’s seventh-order KdV equation [39].

In the present work, our main purpose is to calculate the generalized fifth-order KdV equation by the extended complex method based on the concept of Yuan et al. [40–46]. It is a remarkable approach to attain exact analytical solutions. Our technique would be potentially applied to various processes of the engineering field. This article is organized as mentioned as follows. In Section 2, methods and materials are described. In Section 3, the application of the introduced method is determined. Section 4 deals with physical phenomena of important results. The comparison and conclusions are explained in Section 5.

#### 2. Methods and Materials

Let us consider the general form of NLPDE where the unknown function is and is a polynomial in and its derivatives.

*Step 1. *A transformation is introduced, and can be introduced in different standard; hence, we have used the transformation such as

*Step 2. *The transform Eq. (2) into nonlinear ODE:
in Eq. (4), where primes are the derivatives w.r.t . This equation is reduced by further integration.

*Step 3. *Let the meromorphic solutions of Eq. (4) have at least one pole, and let us consider . For this condition, we substitute the Laurent series
into Eq. (4), if we can find distinct Laurent singular parts:
then the weak condition of Eq. (4) holds. Weierstrass elliptic function with double periods of the equation is given as below:
and the addition formula is mentioned as below:

*Step 4. *Putting the indeterminate forms
into Eq. (4); hence, the number of equations is computed by adjusting the coefficient to zero. These algebraic equations are calculated by the source of maple. Equation (9) is the elliptic solution with pole at , where are attained by (4), , . Equation (10) is the rational function, and Eq. (11) is the exponential function which are denoted as , and they have distinct poles of multiplicity .

*Step 5. *The meromorphic solutions are got with the arbitrary pole. Substitute inverse transformation into meromorphic solutions; then, we obtain the exact analytical solutions of NLPDEs.

#### 3. Application of the Method

In this section, we would like to find the exact analytical solutions of a generalized fifth-order KdV equation by extended complex approach. Substitute into Eq. (1), then obtain now, we integrate Eq. (13) w.r.t ; then, we attain new ODE

Putting (5) into (14) then we have and ; hence, the weak condition of (14) holds. By weak and (10), then rational solutions with pole at are substituting the into Eq. (14); then, we have where

By assuming that the coefficients of same powers concerning in Eq. (16) are zero, then we have numbers of equations:

By solving number of these equations, we obtain then where and ; then

where and .

is a rational function of , applying it into Eq. (14) then substituting into the Eq. (23), we attain that where

By assuming that the coefficients of the same powers concerning in Eq. (25) are zero, then obtain the numbers of equations:

Solve the numbers of these equations, then attain where . so, we obtain the simply periodic solutions of Eq. (14) with pole at where and . Furthermore, where . so, we attain again the simply periodic solutions of Eq. (14) with pole at where and .

By the weak condition, so, we introduce here the elliptic solutions by (9) with pole. substitute into Eq. (14); then, we have where

By assuming that the coefficients of the same powers concerning in Eq. (35) are zero, then obtain the numbers of equations:

Solve these equation; then, we have and then we have hence, the elliptic general solutions of Eq. (14) with arbitrary pole are expressed such as where .

Applying the additional formula to the , and we attain where , , , , and and are the arbitrary constants.

By the above approach, so, we obtain the meromorphic solutions of Eq. (14) with arbitrary pole as mention as follows: where , , and . where , , and . where , , and . where , , and .

#### 4. Description about Figures

Here, we display the exact solutions for , , , and by graphical phenomena as in Figures 1–8. These graphs are represented by the source of maple to persuade important results. Figures 1–8 display different multisolitary wave solutions that are obtained by different values of and , whereas other parameters are constant.

Figures 1 and 2 indicate the exact solutions for , adjust the values , , , , and and , , , , and .

Figures 3 and 4 indicate the exact solutions for , adjust the values , , , , , and and , , , , , and .

Figures 5 and 6 indicate the exact solutions for , adjust the values , , , , , and and , , , , , and .

Figures 7 and 8 indicate the exact solutions for , adjust the values , , , , , , and and , , , , , , and .

#### 5. Comparison and Conclusion

Khan et al. [25] represented the modified simple equation technique for the analytical treatment of generalized fifth-order KdV equation. This proposed technique provides fresh exact solutions in the area of engineering and mathematical physics. The results demonstrated the remarkable exact solutions for this technique. For this purpose, we create the comparison between the modified simple equation technique and the extended complex approach.

We employed the extended complex technique to explore the exact analytical solutions of the generalized fifth-order KdV equation. The graphical phenomena are showed by setting the values of arbitrary parameters, and the graphical representations are revealed the mechanism of wave behavior, for example, Figures 1–8 depict that different multisolitary wave solutions are attained by different values of and , whereas other parameters are constant. The extended complex approach is calculated by the source of maple software. This approach is a powerful analytical technique since it provides different new exact solutions which are indicated by the forms of rational, periodic, and elliptic function solutions. These results have been obtained by the extended complex technique to show a deeper understanding of physical structures and provide remarkable exact solutions of higher degree NPDEs.

#### Data Availability

The data used to support the finding of this study are mentioned in the article.

#### Conflicts of Interest

The authors mentioned here that they have no conflict of interests.

#### Acknowledgments

This work is supported by the NSFC (11901111) and Visiting Scholar Program of Chern Institute of Mathematics.