Nonlinear Partial Differential Equations Research Articles

A new identification of Lagrange multipliers to study solutions of nonlinear Caputo–Fabrizio fractional problems

This research aims to provide a new identification of Lagrange multipliers using a novel hybrid method based on the Khalouta transform method and the variational iteration method and to study the solutions of nonlinear fractional problems. This method is called Khalouta variational iteration method (KHVIM). The fractional derivative is considered in Caputo–Fabrizio sense. The uniqueness and convergence results are investigated using Banach fixed point theorem. The results are obtained in the form of successive approximations corresponding to the proposed problem. To demonstrate the accuracy and effectiveness of the proposed method, three different nonlinear fractional partial differential equations are provided. Approximate solutions of the fractional equations were obtained. These solutions quickly converged to exact solutions with lower computational cost. Furthermore, the method used in this study is more generalized and allows our results to be more extensive and cover several new and existing fractional problems in the literature.

On nonlinear buckling of microshells

Investigation of the geometrical nonlinear action of doubly curved shell panels (DCSPs) in micro scale is the main target of this paper. The proposed microshell panels (MSPs) are assumed to be made of an auxetic honeycomb core (AHOC), leading to negative magnitudes of Poisson's ratio, covered by two nanocomposite enriched coating layers (NCECLs). To conduct the size-dependent nonlinear analysis and achieve the corresponding nonlinear equilibrium path (EQP) of the proposed MSPs, the nonlocal strain gradient theory (NLSGT) is utilized. The governing equations containing the equilibrium and compatibility nonlinear partial differential equations in terms of the deformation components are analytically solved based on the Galerkin technique for different types of simply-supported panels. The achieved results of the present solution exhibit the fact that nonlocal and material length scale parameters significantly affect the EQP of the proposed MSPs especially at their post-buckling stage during their snap-through instability. By solving several numerical examples, the effects of various parameters on the size-dependent EQP of the proposed MSPs are investigated. The results indicate that the influences of size-dependency are significantly affected by the curvature and also boundary conditions of the microshells.

Optical solutions for perturbed conformable Fokas–Lenells equation via Kudryashov auxiliary equation method

This paper is dedicated to the study of optical soliton solutions for the perturbed Fokas–Lenells equation with conformable derivative using the Kudryashov auxiliary equation method. The studied optical solutions include a class of categories, comprising dark, mixed dark-bright, multi bell-shaped, bell-shaped, and wave optical solutions. Furthermore, we analyzed the magnitude of the perturbed conformable Fokas–Lenells equation by investigating the impact of the conformable parameter and the effect of the time parameter on the novel optical solutions. It can be claimed that the current optical soliton solutions are novel and have not existed in the literature. The results obtained illustrate that the proposed method is robust, efficient, and readily applicable for constructing new solutions to a wide range of nonlinear fractional partial differential equations. The results of this study are expected to shed light on the field of soliton theory in nonlinear optics and mathematical physics.

MHD Casson ternary hybrid nanofluid flow through a vertical porous plate with thermal radiation: A finite difference approach

AbstractThis entire study aims to investigate the impacts of linear thermal radiation and MHD Casson ternary hybrid nanofluid flows over a vertical porous plate for comparison of nanofluid, hybrid, and tri‐hybrid nanofluids with Newtonian and non‐Newtonian fluids. We used a ternary hybrid nanofluid, Blood contains three types of oxides and metals: spherical ferric oxide (Fe3O4), platelet‐shaped zinc (Zn), and cylindrically‐shaped gold (Au) nanoparticles. The coupled nonlinear dual partial differential equations (PDEs) are turned into PDEs using nondimensional quantities. The Finite Difference Method (FDM) and the Perturbation Method are then used to solve the PDEs. The impacts of different parameters on temperature, velocity, Nusselt number, and Skin friction profiles have been discussed. The increase in viscosity occurs because an increase in Gr also causes an increase in the velocity field for nanofluid, hybrid, and tri‐hybrid nanofluids. A tri‐hybrid nanofluids performs better among the three, such as nanofluid, hybrids and tri‐hybrid nanofluids. As the volume fractions (Fe3O4) increase, the temperature increase for both Newtonian and non‐Newtonian fluids. The increase in temperature is due to the thermal conductivity of nanoparticles, which is enhanced by growth estimates of the nanoparticle volume fraction. The high temperature of the fluid is observed for large estimates of nanoparticle volume fraction. An increase gold (Au) also increases the temperature for shapes (cylinder, platelet, and spherical). A spherical shape performs better among the three, such as cylinder, platelet, and spherical. In this model, biomedical applications such as antiviral and therapeutic, treatment of the COVID‐19 virus, cancer treatment, and anticancer medication delivery systems.

Numerical study of nonlinear time-fractional Caudrey–Dodd–Gibbon–Sawada–Kotera equation arising in propagation of waves

In this manuscript, the numerical approximation of the solution for time-fractional Caudrey–Dodd–Gibbon–Sawada–Kotera (CDGSK) nonlinear partial differential equation is described involving the Caputo fractional derivative with the help of two novel techniques namely, Sumudu Residual Power Series (SRPS) method and Homotopy Perturbation Sumudu Transform (HPST) method. CDGSK equation describe the propagation of capillary waves and shallow water waves. The results obtained through numerical approximation shows that both SRPS and HPST under consideration are reliable and efficient. The present framework precisely reflects the behavior of the obtained result for various fractional orders. Additionally, we conduct a comparison between the exact solution and an approximate series solution to affirm the efficacy of the proposed techniques. This analysis highlights the efficiency and precision of both techniques in solving nonlinear fractional differential equations. All the numerical simulations are demonstrated graphically using Maple and Matlab.

Dynamics of invariant solutions of the DNA model using Lie symmetry approach

The utilization of the Lie group method serves to encapsulate a diverse array of wave structures. This method, established as a robust and reliable mathematical technique, is instrumental in deriving precise solutions for nonlinear partial differential equations (NPDEs) across a spectrum of domains. Its applications span various scientific disciplines, including mathematical physics, nonlinear dynamics, oceanography, engineering sciences, and several others. This research focuses specifically on the crucial molecule DNA and its interaction with an external microwave field. The Lie group method is employed to establish a five-dimensional symmetry algebra as the foundational element. Subsequently, similarity reductions are led by a system of one-dimensional subalgebras. Several invariant solutions as well as a spectrum of wave solutions is obtained by solving the resulting reduced ordinary differential equations (ODEs). These solutions govern the longitudinal displacement in DNA, shedding light on the characteristics of DNA as a significant real-world challenge. The interactions of DNA with an external microwave field manifest in various forms, including rational, exponential, trigonometric, hyperbolic, polynomial, and other functions. Mathematica simulations of these solutions confirm that longitudinal displacements in DNA can be expressed as periodic waves, optical dark solitons, singular solutions, exponential forms, and rational forms. This study is novel as it marks the first application of the Lie group method to explore the interaction of DNA molecules.

Editorial Conclusion for the Special Issue “New Theory and Applications of Nonlinear Analysis, Fractional Calculus and Optimization”

Nonlinear analysis has widespread and significant applications in many areas at the core of many branches of pure and applied mathematics and modern science, including nonlinear ordinary and partial differential equations, critical point theory, functional analysis, fixed point theory, nonlinear optimization, fractional calculus, variational analysis, convex analysis, dynamical system theory, mathematical economics, data mining, signal processing, control theory, and many more [...]

Can physics-informed neural networks beat the finite element method?

Abstract Partial differential equations play a fundamental role in the mathematical modelling of many processes and systems in physical, biological and other sciences. To simulate such processes and systems, the solutions of PDEs often need to be approximated numerically. The finite element method, for instance, is a usual standard methodology to do so. The recent success of deep neural networks at various approximation tasks has motivated their use in the numerical solution of PDEs. These so-called physics-informed neural networks and their variants have shown to be able to successfully approximate a large range of partial differential equations. So far, physics-informed neural networks and the finite element method have mainly been studied in isolation of each other. In this work, we compare the methodologies in a systematic computational study. Indeed, we employ both methods to numerically solve various linear and nonlinear partial differential equations: Poisson in 1D, 2D, and 3D, Allen–Cahn in 1D, semilinear Schrödinger in 1D and 2D. We then compare computational costs and approximation accuracies. In terms of solution time and accuracy, physics-informed neural networks have not been able to outperform the finite element method in our study. In some experiments, they were faster at evaluating the solved PDE.

A novel analytical technique for analyzing the (3+1)-dimensional fractional calogero- bogoyavlenskii-schiff equation: investigating solitary/shock waves and many others physical phenomena

This work presents a thorough analysis of soliton wave phenomena in the (3+1)-dimensional Fractional Calogero-Bogoyavlenskii-Schiff equation (FCBSE) with Caputo’s derivatives through the use of a novel analytical technique known as the modified Extended Direct Algebraic Method (mEDAM). By converting nonlinear Fractional Partial Differential equations (FPDE) into integer-order Nonlinear Ordinary Differential equations (NODE), and then using closed-form series solutions to translate the NODE into an algebraic system of equations, this method allows us to derive families of soliton solutions, which include kink waves, lump waves, breather waves, and periodic waves, exposing new insights into the behavior and distinctive features of soliton waves in the FCBSE. By including contour and 3D graphics, the behaviors of a few selected soliton solutions are well depicted, showcasing their amplitude, shape, and propagation characteristics. The results enhance our understanding of the FCBSE and show that the mEDAM is a valuable tool for studying soliton wave phenomena. This work creates new opportunities for studying wave phenomena in more intricately constructed nonlinear FPDEs (NFPDEs).

Stability analysis and retrieval of new solitary waves of (2+1)- and (3+1)-dimensional potential Kadomtsev–Petviashvili and B-type Kadomtsev–Petviashvili equations using auxiliary equation technique

The Kadomtsev–Petviashvili (KP) equations are nonlinear partial differential equations which are widely used for the modeling of wave propagation in hydrodynamic and plasma systems. This study aims to make a valuable contribution to the literature by providing new solitary waves to the (2+1)- and (3+1)-dimensional potential Kadomtsev–Petviashvili (pKP)-B-type Kadomtsev–Petviashvili (BKP) equations. For this, the auxiliary equation method associated with Bernoulli equation is used and new solutions for the considered equations are obtained. The stability of obtained solutions is demonstrated using nonlinear analysis. It is shown that this method for the considered pKP–BKP equations is an important step forward in an overall mathematical framework for similar equations.

Explicit and exact travelling wave solutions for Hirota equation and computerized mechanization.

By using the power-exponential function method and the extended hyperbolic auxiliary equation method, we present the explicit solutions of the subsidiary elliptic-like equation. With the aid of the subsidiary elliptic-like equation and a simple transformation, we obtain the exact solutions of Hirota equation which include bright solitary wave, dark solitary wave, bell profile solitary wave solutions and Jacobian elliptic function solutions. Some of these solutions are found for the first time, which may be useful for depicting nonlinear physical phenomena. This approach can also be applied to solve the other nonlinear partial differential equations.

ON THE PERIODIC SOLITON SOLUTIONS FOR FRACTIONAL SCHRÖDINGER EQUATIONS

In this research, we use a novel version of the Extended Direct Algebraic Method (EDAM) namely generalized EDAM (gEDAM) to investigate periodic soliton solutions for nonlinear systems of fractional Schrödinger equations (FSEs) with conformable fractional derivatives. The FSEs, which is the fractional abstraction of the Schrödinger equation, grasp notable relevance in quantum mechanics. The proposed gEDAM technique entails creating nonlinear ordinary differential equations via a fractional complex transformation, which are then solved to acquire soliton solutions. Several 3D and contour graphs of the soliton solutions reveal periodicity in the wave profiles that offer crucial perspectives into the behavior of the system. The work sheds light on the dynamics of FSEs by displaying numerous families of periodic soliton solutions and their intricate relationships. These results hold significance not only for comprehending the dynamics of FSEs but also for nonlinear fractional partial differential equation applications.

Impacts of activation energy and electroosmosis on peristaltic motion of micropolar Newtonian nanofluid inside a microchannel

This study investigates the impact of electroosmosis on the peristaltic flow of unsteady micropolar nanofluid with heat transfer. The findings could enhance the design of peristaltic pumps, potentially improving drug delivery systems, simulations of blood flow in medical devices, and cancer treatments. The fluid under investigation adheres to a micropolar model and flows through a microchannel that exhibits peristalsis along its walls. Moreover, the system is subjected to various external effects, including a uniform magnetic field, the electroosmotic phenomenon, heat absorption, and a chemical reaction with activation energy. Consequently, the problem is mathematically modulated by a system of nonlinear partial differential equations governing the velocity, temperature, and nanoparticle concentration. By employing wave transformation, these governing equations are reduced to ordinary differential equations (ODEs). The reduced equations were solved both analytically, using the homotopy perturbation method, and numerically, using the Runge–Kutta–Merson method. A comparison was made between the solutions, which were found to be closely aligned. Furthermore, a series of figures were employed to provide visual representation and discussion of the implications of the physical properties. The calculations reveal that the electroosmotic flow (EOF) enhances the axial flow of the micropolar fluid along the direction of the applied electric field. It is also observed that the increase in the activation energy (which indicates a low reaction rate) increases the concentration profile whereas the increase in the reaction rate parameter reduces the concentration profile. Additionally, the spin velocity of the particles is diminished by either an increase in the magnetic parameter or the coupling parameter.

Magnetohydrodynamic Marangoni fluid flow, heat, and mass transfer over a radially stretching disk in the presence of heat generation and chemical reaction

The analysis of magnetohydrodynamic (MHD) Marangoni fluid flow, heat, and mass transport over a disk is considered in this article. The fluid is assumed to pass radially over a stretching disk. Suction/blowing at the boundary, internal heat generation/absorption, and a first-order chemical reaction are also considered. By using appropriate similarity transformations, the governing nonlinear partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs). These ODEs along with the appropriate boundary conditions for the model are solved numerically by a shooting technique using MATHEMATICA software. The obtained results are compared with the available results in the literature for some special cases. The effects of the magnetic parameter, the Marangoni number, Marangoni ratio parameter along with the other pertinent parameters on fluid flow, heat and mass transport are analyzed and discussed in detail. It is noted that higher magnetic field depresses the fluid velocity whereas the fluid temperature and fluid concentration are uplifted with an increase in the magnetic field parameter. A quite opposite behavior is observed for Marangoni number. Marangoni ratio parameter boosted the fluid velocity as well as the fluid concentration and the temperature. Also externally applied suction significantly affects the fluid behavior. Increasing chemical reaction parameter reduces the fluid concentration. It is observed that a maximum increase in the Nusselt number occurs for Marangoni parameter Ma, which is 34.75595% when the suction/injection parameter s = 0.5. Also, for Marangoni ratio parameter Ra, a maximum increase in Nusselt number occurs, which is 6.7884% when suction/injection parameter s = 0.5.

Linear and nonlinear stretching sheet for enhanced heat and mass transfer in Casson nanofluid with activation energy

In this study, we delve into the magnetohydrodynamic heat and mass transfer flow of a Casson nanofluid over specifically chosen linear and nonlinear stretching surfaces embedded in a porous medium to understand their distinct effects on fluid behavior. By focusing on the influences of Brownian motion, thermophoresis, thermal radiation, and chemical reactions, we transformed nonlinear partial differential equations into ordinary differential equations, leveraging the Runge-Kutta method and Shooting Techniques for numerical solutions of momentum, temperature, and concentration profiles under predetermined boundary conditions. Our results, depicted in both graphical and tabular forms, shed light on how various parameters, including the Casson fluid characteristics, magnetic fields, buoyancy ratio, and mixed convection effects, influence fluid dynamics. A notable finding is that an increase in the Brownian motion parameter intensifies the fluid velocity and temperature profiles, but reduces its concentration profile, unveiling complex interactions within the nanofluid dynamics. This investigation underscores the importance of linear and nonlinear stretching surfaces in mimicking practical industrial scenarios, thereby providing insights that are crucial for optimizing processes such as coating, cooling of electronic devices, and in the manufacturing of thin plastic films, where precise control over heat and mass transfer is essential.

Feasibility of integrated numerical and Adaptive Neuro-Fuzzy Inference System models in predicting the thermophysical properties of unsteady coupled micropolar–Casson hybrid nanofluids

This article aims to probe postulated phenomena using a paired micropolar and Casson hybrid fluid over a rotating disk. The intension to design a numerical technique (Runge–Kutta fourth-order along with shooting technique) integrated Adaptive Neuro-Fuzzy Inference System (ANFIS) envisioned with a thermal and exponentially space-dependent heat source, nonlinear thermal radiation and entropy production is developed in this phase of work. To ensure that, a nonlinear partial differential equation set of equations has been transformed into an ordinary differential equation by using the proper self-similarity variables. The model's research results, with a few notable outliers, are mostly consistent with those from prior research that was merged into the dataset used to train the ANFIS model. With the impact of active factors, the results are esthetically exhibited for numerous profiles. This displays that with the rise in magnetic field and radiation, the velocity and temperature profiles increase sharply, resulting in a contradiction phenomenon with the decreasing electric field inputs. Also, tilting of vortex viscosity, spin gradient viscosity and microinertia density on the various microrotation components displays inclination. Moreover, ANFIS training was exploited to analyze the approximate solutions for specific scenarios, and the developed ANFIS was evaluated against a testing dataset to emphasize its performance. Due to their longer render, the nanoparticles exploited here are deemed suitable for use in bone implants, iodinated agents for blood imaging and red blood cell stimulation. Thus, the results of this study may be applied to therapeutic anemia therapies.

Combined effects of rotating and thermal radiation on heat and mass transfer of MHD flow in converging and diverging channels

ABSTRACT Current study deals with influence of rotating and thermal radiative fluxing on fluid’s thermal, hydrodynamic, and concentration behavior flowing between two nonparallel walls in existence of uniform magnetized force. The modeling is based on nonlinear partial differential equations (PDEs) such as continuity, momentum, temperature, and concentricity equations. These equations are converted into a system of nonlinear ordinary differential equations (ODEs) utilizing similarity transformations. Analytical solution has been constructed using the Differential Transform Method (DTM). The present results are compared to results obtained by the HAM package and by the numerical procedure (RKF-45) for validation. The impacts of active variables like the rotational factor, Hartmann, Schmidt numbers, and thermal radiation parameter, are investigated on the rapidity, temperature, and concentricity profiles. Moreover, frictional force factor, Nusselt, and Sherwood quantities. It is found that speed and concentricity of the fluid flow increase with the growth of Hartmann number, whereas a reverse behaviour is observed for thermal distribution. Results obtained also reveal an improvement in frictional force factor, Nusselt and Sherwood numbers with the enhancement of Reα parameter. It is found that an increase in the rotational parameter Ro and the radiation factor Rd leads to a decrease in the Nusselt number.

Nanoparticle aggregation and electro-osmotic propulsion in peristaltic transport of third-grade nanofluids through porous tube

In the modern era, the utilization of electro-kinetic-driven microfluidic pumping procedures spans various biomedical and physiological domains. The present study introduces a mathematical framework for characterizing the hemodynamics of peristaltic blood flow within a porous tube infused with ZrO2 nanoparticles. This model delves into the interactions between buoyancy, electro-osmotic forces, and aggregated nanoparticles to discern their influence on blood flow. We employ a third-grade fluid model to elucidate the rheological behavior of the pseudoplastic fluid which refers to its response to applied shear stress, specifically the relationship between shear rate and viscosity. The collective influence of accommodating heat convection, joule heating and aggregated nanoparticles contributes to the thermal behavior of fluids. The distribution of electric potential within the electric double layer (EDL) is predicted by solving the Poisson–Boltzmann equation. The rescaled equations are simplified using the lubrication and Debye-Hückel models as the underlying frameworks. The novel homotopy perturbation method is employed to obtain solutions for the finalized non-linear partial differential equation. Theoretical assessment of hemodynamic impacts involves plotting graphical configurations for various emerging parameters. As electro-osmotic parameter increase, the bloodstream encounters greater impedance, thereby enhancing the effectiveness of electro-osmotic assistance. Concurrently, elevated convective heat markedly reduces the rate of heat transfer, potentially resulting in a drop in blood temperature. It is important to note that maximum shear stress occurs when the artery is positioned horizontally, underscoring the significant impact of arterial alignment on wall shear stress. Skin friction intensifies with the increasing wall permeability as aggregated nanofluids pass through the arterial conduit. Therefore, aggregation of nanoparticles into the bloodstream yields a broader spectrum of distinctive physiological features. In summary, these findings enable more effective tool and device designs for addressing medication administration challenges and electro-therapies.

Periodic Optimal Control of a Plug Flow Reactor Model with an Isoperimetric Constraint

AbstractWe study a class of nonlinear hyperbolic partial differential equations with boundary control. This class describes chemical reactions of the type “$$A \rightarrow $$ A → product” carried out in a plug flow reactor (PFR) in the presence of an inert component. An isoperimetric optimal control problem with periodic boundary conditions and input constraints is formulated for the considered mathematical model in order to maximize the mean amount of product over the period. For the single-input system, the optimality of a bang-bang control strategy is proved in the class of bounded measurable inputs. The case of controlled flow rate input is also analyzed by exploiting the method of characteristics. A case study is performed to illustrate the performance of the reaction model under different control strategies.

WELL-POSEDNESS OF A NONLINEAR INTERFACE PROBLEM DESCRIBED BY HEMIVARIATIONAL INEQUALITIES VIA BOUNDARY INTEGRAL OPERATORS

AbstractThis paper is devoted to the well-posedness of a novel nonlinear interface problem on an unbounded domain with nonmonotone set-valued transmission conditions. This interface problem involves a nonlinear monotone partial differential equation in the interior domain and the Laplacian in the exterior domain. Such a scalar interface problem models nonmonotone frictional contact of elastic infinite media. The variational formulation of the interface problem leads to a hemivariational inequality (HVI), which however lives on the unbounded domain, and thus cannot be analyzed in a reflexive Banach space setting. Boundary integral methods lead to another HVI that is amenable to functional analytic methods using standard Sobolev spaces on the interior domain and Sobolev spaces of fractional order on the coupling boundary. Broadening the scope of the paper, we consider extended real-valued HVIs augmented by convex extended real-valued functions. Under a smallness hypothesis, we provide existence and uniqueness results and, moreover, establish a stability result for extended real-valued HVIs with respect to the extended real-valued function as a parameter. Based on the latter general stability result, we provide various stability results for the interface problem, as well as the stability of a related bilateral obstacle interface problem with respect to the obstacles.