Abstract

In this article, an optimization strategy is presented for the numerical solution of Burgers’ equations, which play an important role in estimating and forecasting pollution. The method involves the exponential B-spline basis function as the basis function in the differential quadrature method. Since exponential B-spline involves a parameter, the artificial bee colony optimization algorithm is implemented to find the unknown parameters that result in the minimum error. Among the metaheuristic optimization algorithms, the artificial bee colony (ABC) is one that has received the greatest attention from researchers and has been successfully implemented to solve various problems in engineering and sciences. The proposed work emphasizes the calculation of the parameter of exponential basis functions, a major factor that plays a role in the error calculation using the ABC optimization algorithm. The acquired findings are provided as tables, and the physical behaviour is showcased in the form of figures and tables. The results are in good conformity with the earlier studies.

1. Introduction

Optimization is the theory of methods that make a mathematical function or system maximally useful or minimize its disadvantages. Optimization methods are used in various disciplines of research to identify solutions that maximize or decrease some parameters of the subject. The purpose of optimization is to discover an optimal or near-optimal solution with little computing effort. There has been a steady increase since 1960s in the pursuit of developing robust algorithms for challenging optimization problems by modelling them after biological systems [1]. Nowadays, while discussing optimization methods, researchers talk about evolutionary algorithms. Goat’s genetic programming [2] and Fogel et al.’s evolutionary algorithm [3] are among the most well-known algorithms in this category; other notable contributors are Holland’s evolutionary methods [4], Rechenberg’s, and Schwefel’s work [5]. Hybrid versions combining several paradigms are also very prevalent. Among the many reports, the work by Back and Schwefel [6], Michalewicz et al. [7], and Fogel [8] has provided a comprehensive overview of the current state of evolutionary algorithms. Perhaps the most well-known evolutionary computing approaches today are genetic algorithms, which are effective stochastic search and optimization strategies with broad applicability. Recently, the genetic algorithm community has focused much of its effort on industrial engineering optimization issues, resulting in a growing amount of research and practical implementations.

Swarm intelligence algorithms [9] have recently caught the attention of numerous research experts in related domains. Swarm intelligence (SI) is the collective behaviour of self-organized systems. Typically, SI systems consist of a population of simple agents interacting locally with one another and their environment. The source of inspiration is frequently nature, particularly biological systems [10]. Fleeces of birds, schools of fish, and colonies of social insects like termites, ants, and bees are all well-known instances of such swarms. Despite the fact that honey bee colonies exhibit the self-organizing features necessary for SI, researchers have been interested in the behaviour of these swarm systems to characterize novel intelligent techniques.

The artificial bee colony (ABC) [11] is one of the metaheuristic optimization algorithms that has received the greatest attention and has been successfully implemented in various applications such as the forecasting of transportation energy and energy demand [12, 13].

Due to the applicability of the ABC algorithm in optimizing the objective function effectively in terms of time and computational complexity, the method is applied in the numerical technique to obtain the unknown parameter. The present work is intended to optimize (minimize) the maximum numerical errors () for the solutions of Burgers’ equation using the differential quadrature method involving an exponential B-spline basis function using artificial bee colony optimization (ABC-EDQ) for the unknown parameter involved in exponential B-spline. The application of the method reduces the considered partial differential equation to an ordinary differential equation (ODE) by approximating the space derivatives through the usage of a differential quadrature method. The subsequent step includes computing the solution to the converted equations through the use of MATLAB solvers.

Burgers’ equation came into existence in 1915 by Harry Bateman [14] followed by Burgers in 1948 [15] and hence was named “Burgers’ equation.” Burgers’ equation makes one think of the Navier–Stokes equation for one dimension. Burgers’ equation is an elementary partial differential equation which is widely practiced for applications in various fields of applied mathematics such as fluid mechanics, nonlinear acoustics, gas dynamics, and traffic flow.

Recently in 2022, researchers established an energy equation combined with the viscous Burgers’ equation as a quantitative model for estimating river water thermal pollution [16]. Thermal pollution is a pollution that causes a decrease in the oxygen level of water, making aquatic life harder. It occurs due to various human activities that includes electric generating plants, steel melting facilities, and industrial boilers. Thermal pollution in rivers, lakes, and waterways can be studied using the energy equation and the viscous Burgers’ equation. The proposed model is a nonlinear system of partial differential equations (PDEs), which may be thought of as an initial and boundary value problem (IBVP). The authors have examined an explicit second-order Lax–Wendroff type technique to obtain the numerical solution of the equation and visually represented the numerical solutions as a temperature profile, which exhibits good qualitative agreement with the real heat transport occurrence.

In the context of pollution, this equation plays an important role. In a work reported by researchers in 2019, Burgers’ equation has also been used as a model to forecast pollution, emphasizing hydro and water pollution [17].

In this paper, the authors propose a correction strategy based on Burgers’ equations to improve the estimation and prediction of pollution.

Burgers’ equation is given by

Here, the coefficient of kinematic viscosity is given as , a parameter which is greater than zero with a small positive value while represents a positive constant which behaves as a driving force.

Due to various applications of Burgers’ equation, there are various well-known numerical methods reported in the literature to solve this equation.

Various well-known numerical methods have been applied to find the numerical solution of Burgers’ equation in the last few years, such as the differential quadrature method (DQM) with modified cubic B-spline [18], cubic B-spline basis functions in standard form [19], modified trigonometric cubic B-spline [20], and exponential modified cubic B-spline [21]. The finite element method has also been applied to the equation with the Hopf–Cole transformation by transforming the equation to the linear heat equation [22] and with the Galerkin finite element approach [23]. The equation has also been experimented with the collocation approach with quadratic B-spline basis functions [24], quartic B-spline [25], cubic B-spline [26], and modified cubic B-splines [27]. Many researchers have also implemented the finite difference approach in different forms, such as the finite difference method, which has been used with the parameter-uniform implicit difference scheme [28], the fourth-order finite difference method [29], and the implicit fourth-order compact finite difference scheme [30].

This is how the research is presented. In Section 1, an introduction to the scheme and its significant contributions in several areas are presented. Following this is an explanation of the numerical scheme in Section 2, which includes a discussion of ABC, exponential B-spline, and their implementation in the differential quadrature method. In Section 3, numerical examples of the equation are provided with various aspects of parameters and for different time levels. The thoughts on the usefulness of the system are included in Section 4.

2. Scheme Description (ABC-EDQ)

The proposed method uses artificial bee colony optimization to establish the parameter for the execution of the exponential B-spline using the differential quadrature method.

2.1. Exponential B-Spline Differential Quadrature Method (EDQ)

The differential quadrature technique is a well-known method for solving partial differential equations that have been used with a variety of basic functions [31]. Many problems, including Fisher’s equation [32], the Telegraph equation [33], the Korteweg-De Vries equation [34], the nonlinear Schrodinger equation [35], and many more, have been successfully solved numerically using this method. This approach has also been used for fractional differential equations [36], indicating its applicability beyond partial differential equations.

To make this method work, first consider the domain x[a, b] as , where N characterizes its distribution. The solution is a smooth function over the solution domain, approximated for its derivatives with respect to x as a linear sum of all functional values in terms of weighting coefficients as follows:

To determine the requisite weighting factors, the suggested method employs exponential B-splines, a version of ordinary B-splines. The purpose is to represent the solution using the features of the B-spline basis function but with the addition of a parameter that depicts the form of the piecewise polynomial. Many attempts have been made to solve different types of differential equations using exponential basis functions, but they have always been limited by the requirement to incorporate a parameter, the value of which has only been approximated intuitively. An exponential B-spline in the piecewise domain is defined as follows:where is the uniform space partition and other parameters are reported as follows:

The numerical values of the function and the derivatives at nodal point can be obtained as follows:

The basic functions at the border grid points are redefined to meet the criterion of a diagonally dominating matrix before the basis function is implemented, as illustrated in [18].

2.2. Artificial Bee Colony Optimization

To optimize numerical issues, Karaboga [37] proposed the artificial bee colony (ABC) algorithm in 2005. The ABC algorithm is a swarm-based metaheuristic algorithm. It was influenced by how honey bees used intelligence in their foraging. Various algorithms, tailored to the unique intelligence of bee swarms, have been created throughout the years. A swarm of bees is a large group of bees that have gathered to form a colony [10]. The primary feature of a swarm is the foraging behaviour of the bees. A bee will collect nectar from a flower and put it in its honeycomb when it discovers a good source of nourishment. Enzymes are produced, and nectar is poured into the hive’s vacated cells to begin the honey-making process. Worker bees dance to communicate with each other and tell each other about the location of potential food sources. They dance in one of the defined ways, depending on how well the food supply is doing economically. Bees perform a dance called the waggle dance to indicate the direction of the sun and, by extension, the location of food sources. How quickly the dance moves indicate the distance between the hive and the food supply. A trembling bee is a sign that the bee is uncertain about the present food supply’s potential for profit [38]. There are a number of parameters involved in defining the algorithm based on the performance of bees. Figure 1 explains the types of bees and their roles. Figure 2 depicts the role of unemployed bees in hunting for food.

2.2.1. Procedure

To find optimal solutions, swarm-based algorithms rely on a cooperative process of trial and error. Peer-to-peer learning’s social colony behaviour is the engine that propels ABC optimization algorithms [39]. ABC generates a set of candidate solutions and then continuously selects the best one. Evolution in an ABC population is driven by variation and selection. Each iteration of the variational process investigates a new region of the search space. The selection process ensures that prior knowledge will be put to good use.

The ABC algorithm comprises four stages: the beginning, when no data are available, the working bees, and the observing phase. Each solution in ABC’s initial population is a dimension vector, and the population is generated randomly. The number of dimensions is proportional to the number of variables in the population’s food-source optimization issue. The seeded bees adjust the current solution based on their own experiences and the fitness benefits of the change. The bee will replace the old food source with the new one if the fitness value of the new food source is greater than the old one. To update the position, the dimension vectors specified in the introductory phase are being used together with the necessary step sizes to calculate the new coordinates. The increment might range from −1 to 1.

The employed bee phase and the position update procedure are shown in Figure 3. Here, Xi indicates where the bee is right now, and the highlighted box indicates the randomly chosen direction. The Xk bee was chosen at random. o achieve this, the random bee’s direction is subtracted from that of the chosen bees. The step size is an arbitrary positive integer that is multiplied by this difference. Finally, this number is added to the vector of dimensions Xi to determine the size of the new food location “V.” This vector is created in the neighbourhood of Xi and has the same metric values.

Bees that are hard at work in the hive share their position and information about the nectar quality of newly developed solutions (food sources). Uninvolved bees analyse the available information and choose the best options based on the fitness probability they offer. The worker bee’s observer counterpart, meanwhile, updates the position in its memory, and evaluates the upcoming resource’s suitability. If the new area is more suitable than the previous one, the bee will remember it and abandon the old one.

If the food source’s location hasn't been updated in a certain amount of time, it has been deemed abandoned. If a food source is abandoned, the bee assigned to it becomes a scout bee and is sent to investigate a new food source elsewhere in the search area. The ABC exit limit, or the predetermined number of cycles, is a key regulating factor. Figure 4 explains the workings of the ABC algorithm in the form of a flow chart that is also presented below as a given pseudocode (Algorithm 1).

Pseudocode of the algorithm:

(1)Input parameters = Population, fit, t, lb, ub, limit, Np.
(2)Calculate objective function value (f) & fitness value (fit).
(3)Set trial = 0.
(4)for i = 1 to t
Evaluate employed bee stage
Determined probability
Apply Onlooker bee phase for generating food source
Memorise the best food source
if trial > limit
 enter into Scout bee stage
end
end

3. Numerical Applications and Discussion

Consider the following boundary values for numerically investigating Burgers’ equation using the provided methodology:and initial conditionsfrom the exact solution on the domain .

When the exponential B-spline differential quadrature technique is used to substitute the space derivatives in Burgers’ equation, the equation is changed into a series of nonlinear ordinary differential equations with time dependence, as shown in the following equation:with .

In this paper, the MATLAB 2014 programming approach is used to determine the numerical solution of the equation while applying EDQ alongside ABC, and the results are displayed as errors. The two test problems presented are considered for determining the numerical answer with the defined approach:

Example 1. Consider Burgers’ equation (1) with domain [0, 2] and zero boundary condition, as well as the initial condition from the precise solution for  = 1. The precise solution obtained analytically is used to verify the equation’s solution as follows:where .
The numerical solution of the problem is achieved at various time levels for at various values. The value of the parameter for the exponential B-spline is derived using ABC for application in the differential quadrature technique. The obtained numerical findings are compared with the exact solutions in Tables 1 and 2 and are reported in the form of errors for t = 0.1 and t = 1 as accessible in the literature.
The important parameters are swarm size: 5, maximum iterations: 50, inertia weight is linearly reduced, and social and cognitive coefficients are c1 = c2 = 2.05. The numerical solutions are in good agreement with the precise solution, as evidenced by the obtained results in the form of and errors.
Figures 5 and 6 depict the physical behaviour of the solution obtained at t = 1 for various values of . From the figures, the physical behaviour of the equation over time can be seen to remain unchanged in behaviour but changing in amplitude.
It can be observed from the results presented in the Tables 1 and 2 that the algorithm has played an important role in minimizing the errors even at the same value of the parameter.

Example 2. Consider the equation (1) to be solved in the domain with boundary and initial condition taken from the exact solution [19] for , given as follows:The numerical solution has been obtained with at different time levels for and .
In Table 3, the errors are estimated at different time levels for time step, and the number of domain partition as 121 and 151, the findings are compared with available data in literature. Using ABC, results are calculated for the parameters in Table 3 considering swarm size: 5; maximum iterations: 20; inertia weight is linearly decreased; and social and cognitive coefficients are taken as and The collected findings show that the numerical results are affected by the parameter as well as the number of domain divisions. The acquired findings are equivalent to the exact solutions that are accessible. Figure 7 depicts the solution behaviour along with the physical behaviour of the equation over time.

4. Concluding Remarks

The ABC technique is used to acquire the parameter for the exponential B-spline-based differential quadrature approach, which is used to calculate the numerical solution to Burgers’ problem. To demonstrate the accuracy of the procedure the problems are solved with the different values of the coefficient of kinematic viscosity ranging from small to high. To illustrate the errors, different time steps and the number of domain divisions are employed. The obtained results are compared to the applied numerical method with particle swarm optimization algorithm in comparison to the ABC algorithm. It can be observed that the errors obtained by ABC algorithm are less as compared to the PSO algorithm when applied for minimizing the error while the value of parameter is same for different applied domain partitions. The proposed strategy presented in the work may be experimented using some other optimization algorithm such as spider monkey and grey wolf optimization algorithm.

Abbreviations

ABC:Artificial bee colony optimization
DQM:Differential quadrature method
E-DQM:Exponential differential quadrature method
SI:Swarm intelligence
IBVP:Initial boundary value problem
PDEs:Partial differential equations.

Data Availability

All data generated or analysed during this study are included in the article.

Disclosure

I hereby declare that the results provided are true and complete to the best of my knowledge and the paper has not been submitted, in whole or in part in any other journal.

Conflicts of Interest

The authors declare that there are no conflicts of interest.