Order Nonlinear Partial Differential Equations Research Articles

The role of dimensions in gravitating relativistic shear-free fluids

We study the dynamics of relativistic shear-free gravitating fluids in higher dimensions for both neutral and charged matter. We reduce the Einstein–Maxwell equations to a single second order nonlinear partial differential equation which contains two arbitrary functions. This generalizes the condition of pressure isotropy to higher dimensions; the new condition is functionally different from four dimensions. Our result in higher dimensions reduces to known results in four dimensions. The presence of higher dimensions affects the dynamics of relativistic fluids in general relativity. The dynamical behaviour of the gravitating fluid in higher dimensions is qualitatively different to the four dimensional case. Higher dimensions affect astrophysical and cosmological processes in gravitating shear-free fluids.

Symplectic geometry of the oil displacement Barenblatt equations

The paper is devoted to the Barenblatt model of oil and water filtration with an admixture of active reagents. This model is used in oil production for hard-to-recover deposits by chemical flooding. The model is described by a system of two first order nonlinear partial differential equations. Conditions for the Buckley–Leverett function, under which the system is reduced to a linear one using symplectic transformations, are found. This makes possible to find classes of exact general solutions of the Barenblatt system and to solve the Cauchy problem.

Learning mesh motion techniques with application to fluid–structure interaction

Mesh degeneration is a bottleneck for fluid–structure interaction (FSI) simulations and for shape optimization via the method of mappings. In both cases, an appropriate mesh motion technique is required. The choice is typically based on heuristics, e.g., the solution operators of partial differential equations (PDE), such as the Laplace or biharmonic equation. Especially the latter, which shows good numerical performance for large displacements, is expensive. Moreover, from a continuous perspective, choosing the mesh motion technique is to a certain extent arbitrary and has no influence on the physically relevant quantities. Therefore, we consider approaches inspired by machine learning. We present a hybrid PDE-NN approach, where the neural network (NN) serves as parameterization of a coefficient in a second order nonlinear PDE. We ensure existence of solutions for the nonlinear PDE by the choice of the neural network architecture. Moreover, we present an approach where a neural network corrects the harmonic extension such that the boundary displacement is not changed. In order to avoid technical difficulties in coupling finite element and machine learning software, we work with a splitting of the monolithic FSI system into three smaller subsystems. This allows to solve the mesh motion equation in a separate step. We assess the quality of the learned mesh motion technique by applying it to a FSI benchmark problem. In addition, we discuss generalizability and computational cost of the learned mesh motion operators.

New applications of the fractional derivative to extract abundant soliton solutions of the fractional order PDEs in mathematics physics

The motive of this research work is to unravel the mysteries of nature through fractional-order partial differential equations (PDEs). Here, we focus on two important fractional order nonlinear PDEs, namely the fractional order (4+1)-dimensional Fokas equation, which is used to give the model of many physical phenomena and dynamical processes, and the other one is the fractional order (2+1)-dimensional breaking soliton equation which is used to analyze the nonlinear problems like optical fiber communications, ocean engineering, etc. Recently, it has been an essential topic to extract the new soliton solutions which are used to investigate the hidden physical conditions of the nonlinear fractional PDEs. So, it is essential to solve those nonlinear fractional PDEs which have a physical impact in the fields of science and modern engineering. In our investigation, we attempt to provide nonlinear wave propagation patterns and investigate the equations, as mentioned earlier, through a computational method. A computing operating software called Mathematica has been applied to get a clear visualization of our gained outcomes, and we ascertain such types of shapes as the bell shape soliton, the anti-bell shape soliton, the singular bell shape soliton, the periodic solution, and the singular periodic solution. Our obtained results can keep an indispensable role in explaining various physical phenomena of nature shortly, and the applied method is the very cogent, efficient, and interesting to extract such types of solutions. Since we extract abundant solutions of these models, so we hope that this article is the best applications of mention method.

Deep learning based solution of nonlinear partial differential equations arising in the process of arterial blood flow

The present work introduces a deep learning approach to describe the perturbations of the pressure and radius in arterial blood flow. A mathematical model for the simulation of viscoelastic arterial flow is developed based on the assumption of long wavelength and large Reynolds number. Then, the reductive perturbation method is used to derive nonlinear evolutionary equations describing the resistance of the medium, the elastic properties, and the viscous properties of the wall. Using automatic differentiation, the solutions of nonlinear evolutionary equations at different time scales are represented using state-of-the-art physics-informed deep neural networks that are trained on a limited number of data points. The optimal neural network architecture for solving the nonlinear partial differential equations is found by employing Bayesian Hyperparameter Optimization. The proposed technique provides an alternate approach to avoid time-consuming numerical discretization methods such as finite difference or finite element for solving higher order nonlinear partial differential equations. Additionally, the capability of the trained model is demonstrated through graphs, and the solutions are also validated numerically. The graphical illustrations of pulse wave propagation can provide the correct interpretation of cardiovascular parameters, leading to an accurate diagnosis and successful treatment. Thus, the findings of this study could pave the way for the rapid development of emerging medical machine learning applications.

Utilizing the extended tanh-function technique to scrutinize fractional order nonlinear partial differential equations

In a range of nonlinear fields, for example molecular biology, physics in plasma, quantum mechanics, elastic media, nonlinear optics, the surface of water waves, and others, many complicated nonlinear behaviors can be pronounced using nonlinear fractional partial differential equations. The nonlinear traveling waves, including nonlinear space-time fractional order differential equations such as the time fractional Sharma-Tasso-Olver (STO) and the space-time fractional Kowerteg-de Vries-Burgers (KdV-Burgers) equations, are analysis through a resourceful approach, namely the extended tanh-function by the definition of the conformable derivative. The stated equations are prevalently used in marine and coastal infrastructure, such as fluid flow, plasma engineering, fiber optics, fusion and fission phenomena, and so on. By renovating fractional order differential equations to ordinary differential equations, fractional order differential transformation simplifies the solution process. Several types of solutions, such as soliton types, bell types, kink types, and some other kinds of results, are developed and portrayed for definite values of free parameters that are plotted in terms of 3D, contour, and spherical shapes. The method is an algebraic approach that is both direct and efficient for dealing with nonlinear equations and yield a distinct category of solutions known as solitons. The suggested method is being used in this study to generate attractive, and effective results that are flexible, easy, and quicker to simulate using general mathematical techniques, namely Maple. It is worth declaring that all resultant solutions are verified for accuracy by exchanging them directly within the original equation through the software package and originating them accurately.MSC: 35C25, 35C07, 35C08, 35Q20, 76B25

Exact solutions of classes of second order nonlinear partial differential equations reducible to first order

This paper illustrates the successful implementation of the method of variation of parameters in combination with the method of characteristics and other techniques to obtain exact solutions for a wide range of partial differential equations. The proposed approach reduces partial differential equations (PDEs) to first-order differential equations, referred to as classical equations, including Bernoulli, Ricatti, and Abel equations. In addition, the techniques proposed have the ability to produce precise solutions for nonlinear second order PDEs. For each PDE class, the method's effectiveness is demonstrated through illustrative examples.

Analyzing the convergence of a semi-numerical-analytical scheme for non-linear fractional PDEs

The purpose of this work is to develop a semi-analytical numerical scheme for solving fractional order non-linear partial differential equations (FOPDEs), particularly inhomogeneous FOPDEs, expressed in terms of the Caputo-Fabrizio fractional order derivative operator. To achieve this goal, we examine several fractional versions of nonlinear model equations from the literature. We then present the proposed scheme, discussing its stability and convergence properties. We show that the proposed scheme is efficient and accurate, and we provide numerical examples to illustrate its performance. Our findings demonstrate that the scheme has significant potential for solving a wide range of complex FOPDEs. Overall, this work contributes to the advancement of numerical techniques for solving fractional order non-linear partial differential equations and lays a foundation for further research in this area.

An efficient numerical method for the time-fractional distributed order nonlinear Klein–Gordon equation with shifted fractional Gegenbauer multi-wavelets method

In this paper, we propose an effective numerical method using two-dimensional Shifted fractional-order Gegenbauer Multi-wavelets to find the approximate solutions of the time-fractional distributed order non-linear partial differential equations. The method is applied to numerically solve the fractional distributed order non-linear Klein–Gordon equation. We derive an exact formula for the Riemann-Liouville fractional integral operator for the Shifted fractional Gegenbauer Multi-wavelets. Applying function approximations obtained by this method turns the considered equation into a system of algebraic equations. Error estimation and convergence analysis of the method are also studied. Some numerical examples are included to show and check the effectiveness of the proposed method.

On solutions for several systems of complex nonlinear partial differential equations with two variables

This article is devoted to describe the entire solutions of several systems of the first order nonlinear partial differential equations. By using the Nevanlinna theory and the Hadamard factorization theory of meromorphic functions, we establish some interesting results to reveal the existence and the forms of the finite order transcendental entire solutions of several systems of the first order nonlinear partial differential equations $$\begin{aligned} \left\{ \begin{aligned}&\left( au_{z_1}+bu_{z_2}\right) \left( cv_{z_1}+dv_{z_2}\right) =e^g,\\&\left( av_{z_1}+bv_{z_2}\right) \left( cu_{z_1}+d u_{z_2}\right) =e^g, \end{aligned} \right. \\ \left\{ \begin{aligned}&\left( au_{z_1}+bv_{z_2}\right) \left( cu_{z_2}+dv_{z_1}\right) =e^g,\\&\left( au_{z_2}+bv_{z_1}\right) \left( cu_{z_1}+dv_{z_2}\right) =e^g, \end{aligned} \right. \end{aligned}$$ and $$\begin{aligned} \left\{ \begin{aligned}&\left( au_{z_1}+bv_{z_1}\right) \left( cu_{z_2}+dv_{z_2}\right) =e^g,\\&\left( au_{z_2}+bv_{z_2}\right) \left( cu_{z_1}+dv_{z_1}\right) =e^g, \end{aligned} \right. \end{aligned}$$ where $$a,b,c,d\in {\mathbb {C}}$$ , and g is a polynomial in $${\mathbb {C}}^2$$ . Moreover, some examples are given to explain that there are significant differences in the forms of solutions from some previous systems of functional equations.

Leading all-loop quantum contribution to the effective potential in general scalar field theory

The RG equation for the effective potential in the leading log (LL) approximation is constructed which is valid for an arbitrary scalar field theory in 4 dimensions. The solution to this equation sums up the leading log ϕ contributions to all orders of perturbation theory. In general, this is the second order nonlinear partial differential equation, but in some cases it can be reduced to the ordinary one. For particular examples, this equation is solved numerically and the LL effective potential is constructed. The solution has a characteristic discontinuity replacing the Landau pole typical for the ϕ4 theory. For a power-like potential no new minima appear due to the Coleman-Weinberg mechanism.

Global dynamics for a collisionless charged plasma in Bianchi spacetimes in Eddington-inspired-Born–Infeld gravity

We consider a Bianchi type I–IX physical metric g, an auxiliary metric q with a collisionless charged relativistic plasma in Eddington-inspired-Born–Infeld theory. We first derive a governing system of second order nonlinear partial differential equations. Then, by the characteristics method applied to the Vlasov equation whose solution is the distribution function f, we manage to construct an iterated sequence. This leads to the existence and uniqueness of a local solution on an interval , with . Then under certain assumptions of smallness on the mean curvatures in both directions, the Eddington parameter k and the dimensionless parameter λ, we show that this solution is global in time.

Spacelike minimal surfaces which are graphs in [formula omitted

In this work we study a system of two second order nonlinear partial differential equations corresponding to the equations of minimal spacelike graphs in the four-dimensional Minkownski space R14. We obtain a set of entire solutions of these equations, adapting the method of Karl Kommerell used for the analogous problem in R4. In our technique we replace ‘‘graphs of holomorphic functions” by ‘‘graphs of generalized harmonic curves” and then we obtain a class of minimal spacelike surfaces in R14 which are also entire graphs with non-zero Gauss curvature. We then provide two versions of the Bernstein Theorem corresponding for the two types of graphs which can occur in R14. Several explicit examples are given.

Stability Analysis and Computational Interpretation of an Effective Semi Analytical Scheme for Fractional Order Non-Linear Partial Differential Equations

In this study we will check the stability of the semi analytical technique, the Laplace variational iteration (LVI) scheme, which is the combination of a variational iteration technique and the Laplace transform method. Then, we will apply it to solve some non-linear fractional order partial differential equations. Since the Laplace transform cannot be applied to non-linear problems, the combination of the variational iteration technique with it will give a better and rapidly convergent sequence. Exact solutions may also exist, but we will show that the coupled technique is much better to approximate the exact solutions. The Caputo–Fabrizio fractional derivative will be used throughout the study. In addition, some possible implications of the results given here are connected with fixed point theory.

Numerical methods for the hyperbolic Monge-Ampère equation based on the method of characteristics

We present three alternative derivations of the method of characteristics (MOC) for a second order nonlinear hyperbolic partial differential equation (PDE) in two independent variables. The MOC gives rise to two mutually coupled systems of ordinary differential equations (ODEs). As a special case we consider the Monge–Ampère (MA) equation, for which we present a general method of determining the location and number of required boundary conditions. We solve the systems of ODEs using explicit one-step methods (Euler, Runge-Kutta) and spline interpolation. Reformulation of the Monge–Ampère equation as an integral equation yields via its residual a proxy for the error of the numerical solution. Numerical examples demonstrate the performance and convergence of the methods.

A Very Simple Procedure for Constructing the Solution of Nonlinear Elliptic PDEs (with Nonlinear Boundary Conditions) Arising from Heat Transfer Problems in Solids

This work presents a procedure for constructing the solution of a second order nonlinear partial differential equation subjected to nonlinear boundary conditions in a very simple and systematic way. The class of equations to be considered here includes, but is not limited to, the partial differential equations which govern the steady-state heat transfer process in bodies with temperature-dependent thermal conductivity and temperature-dependent internal heat source. In addition, it will be considered a large class of nonlinear boundary conditions, especially those arising from the description of the heat exchange process from/to bodies at high temperature levels. Proofs of the solution’s existence and uniqueness are presented.

Analysis of the partially ionized kerosene oil-based ternary nanofluid flow over a convectively heated rotating surface

Abstract The main goal of this inspection is to explore the heat and mass transport phenomena of a three-dimensional magnetohydrodynamic (MHD) flow of ternary hybrid nanoliquid through a porous media toward a stretching surface. Nowadays, the low thermal conductivity is the key problem for scientist and researchers in the transmission of heat processes. Therefore, in order to improve the thermal conductivity of different base liquids, the scientist and researchers are mixing numerous types of solid particles in the base fluids. That is why the authors have mixed three different types of nanoparticles such as graphene oxide, silver, and copper in a kerosene oil base liquid. The influences of Hall current and ion-slip are also considered. Furthermore, the flow behavior is analyzed under the appliance of Darcy–Forchheimer, activation energy, and chemical reaction. By using the concept of boundary layer theory, the flow equations are modeled in the form of higher order nonlinear partial differential equations (PDEs) along with convective boundary conditions. Suitable similarity transformations are used for the transformation of higher order PDEs into the higher order nonlinear ordinary differential equations (ODEs). Analytical scheme known as the homotopic scheme is utilized for the simulation of the current problem. The impacts of discrete flow parameters on the velocities, temperature, and concentration profiles of the ternary hybrid nanoliquid are inspected. The skin friction coefficients, Nusselt number, and Sherwood number of the ternary hybrid nanofluid are investigated against various flow parameters. The outcomes of the current analysis showed that primary velocity of the ternary hybrid nanoliquid is augmented via Hall current and ion-slip number, while the reverse trend is observed via porosity parameter, Darcy–Forchheimer parameter, and magnetic field parameter. On the other hand, the higher values of Hall current and magnetic parameter enhanced the secondary velocity of the ternary hybrid nanoliquid, while the secondary velocity was reduced due to the increasing ion-slip number and rotation parameter. It is found that the heat transfer rate of the ternary hybrid nanofluid is 46% greater than the silver nanofluid.

An encyclopedia of Kudryashov’s integrability approaches applicable to optoelectronic devices

Purpose:In the last decades, many researchers have performed their best in order to find the solution of the nonlinear evolution equations, nonlinear partial differential equations (NLPDEs), fractional nonlinear partial differential equations and nonlinear optical models by using Kudryashov methods, which have various forms. However, most researchers have used different methods under the same name or applied the same method under the different names. This situation has created confusion for researchers and readers, such as choosing the appropriate method, algorithm and the right article title. In order to eliminate this problem and to clarify the methods, we have conducted rigorous research and wrote a certain standard in this field by bringing together the Kudryashov methods, which are widely used under different names in the literature. Besides, it has been aimed to give the general algorithm of the methods, to make some addendums on the methods and to present new approaches to these methods for the researchers. We strongly believe that the study will be of great benefit not only for those who are interested in nonlinear evolution problems, but also for studies in the field optics. Methodology:Regarding the methods, first of all, the articles of the researchers who suggested the methods and the studies of the respected researchers in this field have been examined and tried to gather under one framework and give a general name with appropriate algorithm for each Kudryashov method. The algorithms and solution functions of each method have been checked on the related Riccati and Bernoulli equations with different softwares (Mathematica, Maple, Matlab, etc.), and confirmed every results carefully. Afterwards, all methods have been applied on (2+1)-dimensional Zoomeron equation for the global test purpose. With the usual standard approach, the nonlinear partial differential form of Zoomeron equation has been transformed into the nonlinear ordinary differential (NODE) form by applying the wave transformation, then each method applied to the NODE form of Zoomeron equation. After these operations, we have obtained a system of linear algebraic equations and their appropriate solutions. By obtaining the appropriate solution sets, the soliton solutions of the Zoomeron equation have been constructed and some selected graphical presentations given. Findings:The results have been obtained from the applications that applied on the Zoomeron equation via Kudryashov methods shows us they can be used widely and effectively in the solution of not only nonlinear evolution problems, but also highly dispersive and higher order nonlinear partial differential equations. It has been seen that all the applied Kudryashov methods give effective results. Besides, controlling and using the parameters in the Kudryashov methods play important role, especially obtaining the effective and desired solution sets. Originality:Based on our detailed research, we could not find any summative study in this area like this one. In addition to all these, some of the approaches and addendums have been presented for the first time in this paper. Besides, (2+1)-dimensional Zoomeron equation has also not been previously solved by some of these methods. It is thought that this study will be used as a reference by many researchers in the future and it will be of great benefit to researchers.

A Study of the Soliton Solutions with an Intrinsic Fractional Discrete Nonlinear Electrical Transmission Line

This study aims to identify soliton structures as an inherent fractional discrete nonlinear electrical transmission lattice. Here, the analysis is founded on the idea that the electrical properties of a capacitor typically contain a non-integer-order time derivative in a realistic system. We construct a non-integer order nonlinear partial differential equation of such voltage dynamics using Kirchhoff’s principles for the model under study. It was discovered that the behavior for newly generated soliton solutions is impacted by both the non-integer-order time derivative and connected parameters. Regardless of structure, the fractional-order alters the propagation velocity of such a voltage wave, thus bringing up a localized framework under low coupling coefficient values. The generalized auxiliary equation method drove us to these solitary structures while employing the modified Riemann–Liouville derivatives and the non-integer order complex transform. As well as addressing sensitivity testing, we also investigate how our model’s altered dynamical framework shows quasi-periodic properties. Some randomly selected solutions are shown graphically for physical interpretation, and conclusions are held at the end.

Homotopic simulation for heat transport phenomenon of the Burgers nanofluids flow over a stretching cylinder with thermal convective and zero mass flux conditions

Abstract This study is focused to elaborate on the effect of heat source/sink on the flow of non-Newtonian Burger nanofluid toward the stretching sheet and cylinder. The current flow analysis is designed in the form of higher order nonlinear partial differential equations along with convective heat and zero mass flux conditions. Suitable similarity transformations are used for the conversion of higher order nonlinear partial differential equations into the nonlinear ordinary differential equations. For the computation of graphical and tabular results, the most powerful analytical technique, known as the homotopy analysis method, is applied to the resulting higher order nonlinear ordinary differential equations. The consequence of distinct flow parameters on the Burger nanofluid velocity, temperature, and concentration profiles are determined and debated in a graphical form. The key outcomes of this study are that the Burger nanofluid parameter and Deborah number have reduced the velocity of the Burger nanofluid for both the stretching sheet and cylinder. Also, it is attained that the Burger nanofluid temperature is elevated with the intensifying of thermal Biot number for both stretching sheet and cylinder. The Burger nanofluid concentration becomes higher with the escalating values of Brownian motion parameter and Lewis number for both stretching sheet and cylinder. The Nusselt number of the Burger nanofluid upsurges due to the increment of thermal Biot number for both stretching sheet and cylinder. Also, the different industrial and engineering applications of this study were obtained. The presented model can be used for a variety of industrial and engineering applications such as biotechnology, electrical engineering, cooling of devices, nuclear reactors, mechanical engineering, pharmaceutical science, bioscience, medicine, cancer treatment, industrial-grid engines, automobiles, and many others.