1. Introduction
In recent years, Haar wavelets have found extensive use in signal processing for communication systems and physics research, particularly when dealing with differential calculus and non-linear problems. Wavelets provide a means to perform algebraic modifications on mathematical models, departing from traditional approaches such as variational approximation. This approach can lead to improved criteria for the actual design process.
[1] | Ataie-Ashtiani, B., & Najafi-Jilani, A. (2007). A higher-order two-dimensional Boussinesq wave model. Journal of Coastal Research, 50, 1183-1187. |
[1]
.
In a study by Lepik
[2] | Bona, J. L., Chen, M., & Saut, J. C. (2002). Boussinesq equations and other systems for small-amplitude long waves in nonlinear dispersive media I: Derivation and linear theory. Journal of Nonlinear Science, 12, 283-318. |
[2]
, the results showed that the HW methodology is a dependable way to solve different integral equations (IE) and PDEs, including both linear and nonlinear DE. Ataie and Najafi
[3] | Bona, J. L., Dougalis, V. A., & Mitsotakis, D. E. (2005). Numerical solution of coupled-KdV systems of Boussinesq equations: II. Generation, interactions and stability of generalized solitary waves. Preprint submitted to Elsevier Science. |
[3]
applied a finite difference approach with a higher-order scheme in time and space to solve a higher multiple-order two-dimensional (2-dim) Boussinesq wave (BW) model. They used this strategy to successfully extract equations. In order to mimic three-dimensional surface waves, Chen and Goubet
[4] | Chen, M. (2009). Numerical investigation of a two-dimensional Boussinesq system. Discrete and Continuous Dynamical Systems, 23(4), 1169-1190. |
[4]
investigated the long-term (L-T) behaviour of sol for a large class of dissipative Boussinesq (D-B) systems. They were able to identify the solutions' long-time asymptotes. The numerical method Chen
[5] | Chen, M., & Goubet, O. (2009). Long-time asymptotic behavior of two-dimensional dissipative Boussinesq systems. Discrete and Continuous Dynamical Systems, 2, 37-53. |
[5]
utilised to solve beginning and boundary value issues in a two-dimensional Boussinesq system (B-S) was the main topic. The suggested approach was effective and precise. Using the conventional Galerkin-finite element approach, Mitsotakis
[6] | Debnath, L. (2002). Wavelet transforms and their applications. Birkhäuser. |
[6]
constructed and quantitatively resolved a two-dimensional Boussinesq system in two spatial dimensions. Mera
[7] | Jiwari, R. (2012). A Haar wavelet quasilinearization approach for numerical simulation of Burgers’ equation. Computer Physics Communications, 183, 2413-2423. |
[7]
concentrated on the creation of two-dimensional boundary circumstances for existing Boussinesq-type equations in order to improve the accuracy and applicability of the models. Using techniques like wavelets, finite difference schemes, numerical methods, and boundary conditions formulation, this research contribute to the understanding and development of methods for solving Boussinesq equations overall. Non-linear Boussinesq System has been the subject of extensive research by many researchers.
The four-parameter Boussinesq systems were developed by Bona et al.
[8] | Kaur, H., Mittal, R. C., & Mishra, V. (2013). Haar wavelet approximate solutions for the generalized Lane-Emden equations arising in astrophysics. Computer Physics Communications, 184, 2169-2177. |
[8]
using the multifaceted Euler formulae that govern free-surface movement. They also developed criteria to aid in selecting the optimal equation from this family in different modelling settings. The analysis of these systems was built on the basis of these criteria. In a related article, Bona et al.
[9] | Lepik, U. (2007). Application of the Haar wavelet transform to solving integral and differential equations. Proceedings of the Estonian Academy of Sciences: Physics and Mathematics, 56(1), 28-46. |
[9]
focused on the numerical generalisation of the solitary wave solutions for two linked Boussinesq-type Kdv systems. They provided numerical experiments that clarified the emergence, evolution, and interaction of these waves. They also investigated the intention of generic beginning into succession representations of these vibrations and assessed the cohesion of these waves under small disruptions. Anotonopoulos et al.
[10] | Lepik, U. (2007). Numerical solution of evolution equations by the Haar Wavelet method. Applied Mathematics and Computation, 185, 695-704. |
[10]
looked at if there were any solutions and whether they were distinct for three initial-boundary-value problems pertaining to the Bona-Smith family of Boussinesq systems. Periodic boundary conditions, reflection, and nonhomogeneous Dirichlet boundary conditions that were utilised at the endpoints of a limited spatial interval contributed to these problems. They demonstrated that the initial-boundary-value problem with Dirichlet charts boundary constraints was locally well-posed in suitable contexts, in contrast to related problems with reflection and periodic boundary conditions, which were globally well-posed given particular starting data limitations. A specific type of Boussinesq systems' internal controllability and stability analysis was the focus of Micu et al.'s
[11] | Mera, M. (2011). Boundary conditions for 2D Boussinesq-type wave-current interaction equations. Civil Engineering Dimension, 13(1), 37-41. |
[11]
study. They identified the relevant linear system's controllable data space for all parameter values. They created straightforward feedback controllers that resulted in exponentially stable closed-loop systems using the newly discovered perfect controllability. These works look at solitary wave solutions, initial-boundary value issues that are well-posed under various boundary scenarios, initial-boundary value (IBV) problems that are well-posed under diverse threshold conditions, internal controllability and stability qualities, and criteria for selecting acceptable equations. This research helps us comprehend Boussinesq systems in general
[12] | Micu, S., Ortega, J. H., Rosier, L., & Zhang, B. Y. (2009). Control and stabilization of a family of Boussinesq systems. Discrete and Continuous Dynamical Systems, 24(2), 273-313. |
[13] | Mitsotakis, D. E. (2009). Boussinesq systems in two space dimensions over a variable bottom for the generation and propagation of tsunami waves. Mathematics and Computers in Simulation, 80, 860-873. https://arxiv.org/abs/0906.2491 |
[12, 13]
.
This work employs Haar wavelet techniques to numerically solve a nonlinear third-order Boussinesq system at several scales, particularly scale-2 and 3. The precise solution is contrasted with the results. The paper compares the performance of scale-2 and 3 Haar wavelet (HW) methods for the non-linear (N-L) three-dimensional (3-dim) Boussinesq-Burger (B-B) system of equations. A number of differential equations have been solved using 3-Scale Haar wavelets in the past, proving their effectiveness in mathematical models governed by these equations. Additionally, these investigations have shown that scale-3 Haar wavelets have higher convergence rates than scale-2 Haar wavelets. To the best of our knowledge, scale-3 Haar wavelets have not yet been used to examine the characteristics of solutions to the equations in the Boussinesq-Burger system. This provides as inspiration for creating a novel methodology to evaluate and contrast the consummation of 2-scale and 3-scale Haar wavelet methods in resolving Boussinesq-Burger's system of equations-governed systems. Unlike the current studies based on Haar scale-2 wavelets, we introduce in this study a scale-3 Haar wavelet approach combined with quasi-linearization in order to achieve greater accuracy in the solution of the nonlinear Boussinesq-Burger's system. This is a new formulation that makes possible greater handling of high nonlinearities and time-dependent source terms, which were not previously handled collectively.
The primary goal of the aforementioned study project is to demonstrate an entirely new numerical method for solving the recently developed Boussinesq-Burger's system of equations in the field of dispersive systems. Scale-2 and scale-3 Haar waveform bases are used in the approach that has been suggested.
The generalized Boussinesq-Burger’s system of non-linear partial differential equation given as
(1)
(2)
Subject to the boundary condition
(4)
And with the constraints at the initial values
(5)
By changing the values of these four parameters (p, q, r, s) distinct variations in the solution space can be noticed. The following is how we ordered our paper. The Haar wavelet is introduced in section 2 along with an operational matrix. In Section-3 discusses Quasi-linearization techniques. Haar wavelets with scale-2 and scale-3 were utilised to solve a nonlinear boussinesq problem in section 4. Section 5 deals with the numerical solutions with boundary conditions with different source term. Section 6 has concluding observations.
2. Haar Wavelet Along with Its Operational Matrix
Wavelet approach has been widely employed in image digital processing, general relativity, mathematical methods, and many other domains in recent years as a powerful mathematical weapon.
Equations (
6), (
7) and (
8) give the mathematical equations for the father wavelet (Scale 3 Haar function) and mother wavelets in the scale 3 Haar wavelet family with dilation factor three.
The scale-3 Haar wavelet integral methodology is used to solve a non-linear system of partial differential equation which are of third order. In which the differential equations maximum derivative is expanded into scale-3 Haar wavelets and the derivatives of low order are graded by integrating the differential equations. The Haar scale-3 wavelet is more accurate and converges faster than the Haar scale-2 wavelet. Using the orthogonality condition in wavelets, every square integrable function defined on the interval [0, 1] may be simply expressed in terms of the infinite sum of Haar wavelet series.
f(x)
Haar Scaling Function
(6)
(7)
(8)
Where , .
The wavelet number, level of resolution (dilation), and translation parameters of the wavelet family are represented by and respectively. With the help of the values of i may be computed using the relationships for even values of and for odd values of . Using this connection for various dilations and translations of we get the wavelet family where and are also known as mother wavelets, while the rest of the wavelets are known as daughter wavelets.
Let us define the collocation points and Discredit the Haar function ; in this way we get the coefficient matrix which has the dimension 3M*3M.
The operational matrix of the integration P, which is 3M square matrix is defined. If the solution process of differential equation of any order. We need to integrate Haar scale-3 wavelets i.e., we employ the integral
(9)
(10)
(11)
Moreover, we introduce
(12)
(13)
(14)
which can explicitly be written as
(15)
(16)
(17)
4. Method of Solution
After applying the quasi-linearization, we have equations (
19), (
20) then using these, non-linear system of partial differential equations (
1), (
2), (
3), (
4), (
5) transformed in to the series of linear differential equations (
21), (
22) we have
(21)
(22)
Subjected to the boundary conditions given by
(23)
(24)
With the constraints on initial values
(25)
Here represent approximation for t in the process of quasilinearization.
(26)
(27)
Integrating the equation (
26) with respect to t with limits of integration we have
(28)
Integrating equation (
28) with respect to x three times them we have
(29)
(30)
(31)
Integrating the equation (
27) with respect to t with limits of integration we have
(32)
Now integrating with respect to x we have
(33)
Differentiating equation (
31) with respect to t we get
(34)
Differentiating equation (
33) with respect to t we get
(35)
Using all these values equation (
1), (
2) becomes
(36)
)
(37)
Now using the Boundary conditions and discretizing the space variable as
tend to
where
,
in the equations (
32), (
34) and substituting the value obtained in the given system of equation are obtained for different value of r.
(38)
(39)
Where the equations (
40), (
41), (
42), (
43), (
44), (
45) and (
46) respectively represents the value of
.
(40)
(42)
(43)
)(44)
(45)
The process of solution starts by taking and and the boundary conditions is given by
and
(46)
The values of coefficient can be calculated successively for different values of r by using these equations (
48), (
49).
Then by putting the values of the wavelet coefficient in the given equation and can obtain numerically approximately solution successively for and for values of r then we have
(49)
(50)
5. Numerical Examples
The MATLAB computer language was used to do numerical calculations and to generate graphical outputs. A discrete form of the Haar scale-2 and Haar scale-3 wavelet series is required to determine the numerical solution of a third order system of PDE using Haar-scale-3 wavelet. As a result, at the initial level of resolution J = 1, the collocation points at the point of discontinuity approach given in equations which is used to pick collocation points
[18] | Younas, Usman & Hussain, Ejaz & Muhammad, Jan & Sharaf, Mohamed & El-Meligy, Mohammed. (2025). Chaotic Structure, Sensitivity Analysis and Dynamics of Solitons to the Nonlinear Fractional Longitudinal Wave Equation. International Journal of Theoretical Physics. 64. https://doi.org/10.1007/s10773-025-05916-8 |
[18]
. The efficacy of the present scheme was tested by analysing the solutions of three issues acquired by the present scheme and calculating absolute errors to explain the applicability of the present scheme for the third order system of PDE.
Numerical Problem-1
Consider the following Non-linear Boussinesq Burger’s System of equations
(51)
Subjected to the boundary conditions are given in equation (
51).
,(52)
,(53)
And with the initial conditions given in equation (
54).
,(54)
The exact solution of the Equation (
52) subjected to the conditions given in Equations (
53) and (
54) for
is
,(55)
Figure 1. Graphical representation of Scale-3 Haar Wavelets for u(x, t), w(x, t) for numerical problem-1.
Table 1. Comparison result achieved from Haar Scale-2 and Haar Scale-3 Method for numerical Problem-1.
Level of Resolution | J = 1 | J = 2 | J =3 |
| 2.089608e-15 | 2.329367e-16 | 2.483600e-18 |
| 2.426703e-21 | 2.467190e-23 | 2.422743e-23 |
| 1.297012e-17 | 1.198329e-17 | 1.227092e-19 |
| 1.923255e-22 | 1.929064e-22 | 2.098233e-24 |
The graphical representation of approximated and exact solutions of Scale-3 Haar wavelet for Problem-1 as shown in above figures. Figures illustrates that the exact and numerical results for J=1 are compatible. Table shows the results about errors like in case of both scale-2 and Scale-3 Haar wavelets.
Numerical Problem-2
Consider the following Non-linear Boussinesq Burger’s System of equations
(56)
Subjected to the boundary conditions are given in equation (
57).
,,,(57)
And with the initial conditions given in equation (
54).
(58)
The exact solution of the Equation (
56) subjected to the conditions given in Equations (
57) and (
58) for
is
(59)
With the defined source term
(60)
Figure 2. Graphical representation of Scale-3 Haar Wavelets for u(x, t), w(x, t) for numerical problem-2.
Table 2. Comparison result achieved from Haar Scale-2 and Haar Scale-3 Method for numerical Problem-2.
Level of Resolution | J = 1 | J = 2 | J =3 |
| 3.147904e-11 | 3.810721e-12 | 3.377801e-14 |
| 3.348911e-13 | 3.438901e-13 | 3.234010e-15 |
| 1.368012e-14 | 1.111456e-14 | 1.156723e-16 |
| 1.100098e-15 | 1.678902e-17 | 2.230089e-22 |
The graphical representation of approximated and exact solutions of Scale-3 Haar wavelet for Problem-2 as shown in above figures. Figures illustrates that the exact and numerical results for J=1 are compatible. Table shows the results about errors like in case of both scale-2 and Scale-3 Haar wavelets.
In above two examples help us to enhance the accuracy of Haar scale-3 wavelet method as compare to Haar scale-2 wavelet method. The higher the resolution J, the more exact the solution approximation. For solving Boussinesq-Burger system of equations, the numerical techniques are reliable and convenient. The simplicity, adaptability, and lack of computational errors are the key benefits of these techniques. The outcomes we obtained from the results of numerical experiments performed on three test problems with the proposed technique, we conclude that the 2D Dispersive equations of third order containing non-linearity can easily be solved with high accuracy and less computational cost by the discussed scheme. We have solved various types of Dispersive equations the use of common MATLAB subprograms makes it more computer-friendly. The proposed scheme for a very small number of collocation points becomes a strong solver for these kinds of partial differential equations and good accuracy is obtained. In comparison to the classical Scale-2 Haar wavelet approach, numerical findings indicate that quasi-linearization using Scale-3 Haar wavelet converges rapidly even for small numbers of grid points. As compared with the Finite Difference Method, the novel Haar scale-3 wavelet method uses fewer grid points but with higher accuracy. The principle of balance achieves stability via iteratively linearizing the nonlinear terms to balance solution accuracy and computational cost. The greatest advantage of the proposed method is that it has better accuracy with fewer computational resources compared to the standard methods. It may require more computational time for extremely large systems due to quasi-linearization iterations.