Numerical Methods for Partial Differential Equations

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Axioms axioms	1.9	-	2012	22.8 Days	CHF 2400	Submit
Computation computation	1.9	3.5	2013	18.6 Days	CHF 1800	Submit
Entropy entropy	2.1	4.9	1999	22.3 Days	CHF 2600	Submit
Mathematical and Computational Applications mca	1.9	-	1996	25.4 Days	CHF 1400	Submit
Mathematics mathematics	2.3	4.0	2013	18.3 Days	CHF 2600	Submit
Symmetry symmetry	2.2	5.4	2009	17.3 Days	CHF 2400	Submit

30 pages, 8417 KiB

Open AccessArticle

Toward a Blood Sensor for an IoT Monitoring: A New Approach for the Design and Implementation of Blood Light Absorption Systems Based on the Finite Element Method and the Diffusion Equation

by Mouna Dhmiri, Yassine Manai and Tahar Ezzedine

Math. Comput. Appl. 2025, 30(2), 33; https://doi.org/10.3390/mca30020033 - 24 Mar 2025

Viewed by 203

Abstract

Non-invasive blood analysis has the power to completely change how doctors identify and track illnesses. This study presents a novel approach for the non-invasive monitoring of red blood cell (RBC) mobility and concentration within capillaries, using photon absorption as a key diagnostic tool. [...] Read more.

Non-invasive blood analysis has the power to completely change how doctors identify and track illnesses. This study presents a novel approach for the non-invasive monitoring of red blood cell (RBC) mobility and concentration within capillaries, using photon absorption as a key diagnostic tool. The research combines optical modeling with the diffusion equation for light propagation, leveraging COMSOL simulations to create a comprehensive framework for understanding RBC dynamics. A two-dimensional geometric model of capillaries with RBCs is developed, where blood flow is modeled as a laminar, incompressible fluid. The Arbitrary Lagrangian–Eulerian (ALE) formulation is employed to account for the fluid–structure interactions, while photon attenuation by the RBCs is analyzed to investigate wavelength-dependent absorption characteristics. The methodology is implemented through a workflow developed with MATLAB’s S-Function builder, consisting of three main components: mesh generation, fluence computing, and Software-in-the-Loop (SIL) verification. The mesh generation process adapts to the target architecture using COMSOL Multiphysics for fluid–structure interaction (FSI) modeling. The fluence computing function solves the diffusion equation to model light intensity attenuation due to RBCs, and the SIL function compares computed results with real-time measurements, ensuring accuracy for potential real-time embedded system applications. The results demonstrate significant wavelength-dependent variations in photon absorption by RBCs, providing insights into the optical behavior of blood in microvascular structures. The findings have important implications for medical imaging, photodynamic therapy, and diagnostic tools, emphasizing the potential of integrating computational models with real-time systems for enhanced performance in biomedical applications. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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22 pages, 345 KiB

Open AccessArticle

A Galerkin Finite Element Method for a Nonlocal Parabolic System with Nonlinear Boundary Conditions Arising from the Thermal Explosion Theory

by Qipeng Guo, Yu Zhang and Baoqiang Yan

Mathematics 2025, 13(5), 861; https://doi.org/10.3390/math13050861 - 5 Mar 2025

Viewed by 424

Abstract

In this paper, we discuss a class of nonlocal parabolic systems with nonlinear boundary conditions arising from the thermal explosion theory. First, we prove the local existence and uniqueness of the classical solution using the Leray–Schauder fixed-point theorem. Then, we analyze three Galerkin [...] Read more.

In this paper, we discuss a class of nonlocal parabolic systems with nonlinear boundary conditions arising from the thermal explosion theory. First, we prove the local existence and uniqueness of the classical solution using the Leray–Schauder fixed-point theorem. Then, we analyze three Galerkin approximations of the system and derive the optimal-order error estimates:

O (h^{r + 1})

in

L^{2}

norm for continuous-time Galerkin approximation,

O (h^{r + 1} + {(Δ t)}^{2})

in the

L^{2}

norm for Crank–Nicolson Galerkin approximation, and

O (h^{r + 1} + {(Δ t)}^{2})

in both

L^{2}

and

H^{1}

norms for extrapolated Crank–Nicolson Galerkin approximation. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

16 pages, 739 KiB

Open AccessArticle

High-Order Finite Difference Hermite Weighted Essentially Nonoscillatory Method for Convection–Diffusion Equations

by Yabo Wang and Hongxia Liu

Math. Comput. Appl. 2025, 30(1), 3; https://doi.org/10.3390/mca30010003 - 3 Jan 2025

Viewed by 621

Abstract

A kind of finite difference Hermite WENO (HWENO) method is presented in this paper to deal with convection-dominated convection-diffusion equations in uniform grids. The benefit of the HWENO method is its compactness, allowing great accuracy to be attained in the solution’s smooth regions [...] Read more.

A kind of finite difference Hermite WENO (HWENO) method is presented in this paper to deal with convection-dominated convection-diffusion equations in uniform grids. The benefit of the HWENO method is its compactness, allowing great accuracy to be attained in the solution’s smooth regions and maintaining the essential nonoscillation in the solution’s discontinuities. We discretize the convection term using the HWENO method and the diffusion term using the Hermite central interpolation schemes. However, it is difficult to deal with mixed derivative terms when solving two-dimensional problems using the HWENO method mentioned. To address this problem, we also employ the Hermite interpolation approach, which can keep the compactness. Lastly, we apply this method to two-dimensional Navier-Stokes problems that are incompressible. The efficiency and stability of the presented method are illustrated through numerous numerical experiments. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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13 pages, 421 KiB

Open AccessArticle

Numerical Solution of Oxygen Diffusion Problem in Spherical Cell

by Soumaya Belabbes and Abdellatif Boureghda

Axioms 2025, 14(1), 4; https://doi.org/10.3390/axioms14010004 - 26 Dec 2024

Viewed by 500

Abstract

This study addresses the diffusion of oxygen in a spherical geometry with simultaneous absorption at a constant rate. The analytical method assumes a polynomial representation of the oxygen concentration profile, leading to a system of differential equations through mathematical manipulation. A numerical scheme [...] Read more.

This study addresses the diffusion of oxygen in a spherical geometry with simultaneous absorption at a constant rate. The analytical method assumes a polynomial representation of the oxygen concentration profile, leading to a system of differential equations through mathematical manipulation. A numerical scheme is then employed to solve this system, linking the moving boundary and its velocity to determine the unknown functions within the assumed polynomial. An approximate analytical solution is obtained and compared with other methods, demonstrating very good agreement. This approach provides a novel method for addressing oxygen diffusion in spherical geometries, combining analytical techniques with numerical computations to efficiently solve for oxygen concentration profiles and moving boundary dynamics. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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22 pages, 2331 KiB

Open AccessArticle

A Novel Hybrid Computational Technique to Study Conformable Burgers’ Equation

by Abdul-Majeed Ayebire, Atul Pasrija, Mukhdeep Singh Manshahia and Shelly Arora

Math. Comput. Appl. 2024, 29(6), 114; https://doi.org/10.3390/mca29060114 - 5 Dec 2024

Viewed by 840

Abstract

A fully discrete computational technique involving the implicit finite difference technique and cubic Hermite splines is proposed to solve the non-linear conformable damped Burgers’ equation with variable coefficients numerically. The proposed scheme is capable of solving the equation having singularity at [...] Read more.

A fully discrete computational technique involving the implicit finite difference technique and cubic Hermite splines is proposed to solve the non-linear conformable damped Burgers’ equation with variable coefficients numerically. The proposed scheme is capable of solving the equation having singularity at

t = 0

. The space direction is discretized using cubic Hermite splines, whereas the time direction is discretized using an implicit finite difference scheme. The convergence, stability and error estimates of the proposed scheme are discussed in detail to prove the efficiency of the technique. The convergence of the proposed scheme is found to be of order

h^{2}

in space and order

{(Δ t)}^{α}

in the time direction. The efficiency of the proposed scheme is verified by calculating error norms in the Eucledian and supremum sense. The proposed technique is applied on conformable damped Burgers’ equation with different initial and boundary conditions and the results are presented as tables and graphs. Comparison with results already in the literature also validates the application of the proposed technique. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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17 pages, 384 KiB

Open AccessArticle

Exponential Convergence and Computational Efficiency of BURA-SD Method for Fractional Diffusion Equations in Polygons

by Svetozar Margenov

Mathematics 2024, 12(14), 2266; https://doi.org/10.3390/math12142266 - 19 Jul 2024

Viewed by 952

Abstract

In this paper, we develop a new Best Uniform Rational Approximation-Semi-Discrete (BURA-SD) method taking into account the singularities of the solution of fractional diffusion problems in polygonal domains. The complementary capabilities of the exponential convergence rate of BURA-SD and the

h p

FEM [...] Read more.

In this paper, we develop a new Best Uniform Rational Approximation-Semi-Discrete (BURA-SD) method taking into account the singularities of the solution of fractional diffusion problems in polygonal domains. The complementary capabilities of the exponential convergence rate of BURA-SD and the

h p

FEM are explored with the aim of maximizing the overall performance. A challenge here is the emerging singularly perturbed diffusion–reaction equations. The main contributions of this paper include asymptotically accurate error estimates, ending with sufficient conditions to balance errors of different origins, thereby guaranteeing the high computational efficiency of the method. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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23 pages, 7396 KiB

Open AccessArticle

A Hybrid Method for Solving the One-Dimensional Wave Equation of Tapered Sucker-Rod Strings

by Jiaojian Yin and Hongzhang Ma

Axioms 2024, 13(6), 414; https://doi.org/10.3390/axioms13060414 - 20 Jun 2024

Cited by 1 | Viewed by 823

Abstract

Simulating surface conditions by solving the wave equation of a sucker-rod string is the theoretical basis of a sucker-rod pumping system. To overcome the shortcomings of the conventional finite difference method and analytical solution, this work describes a novel hybrid method that combines [...] Read more.

Simulating surface conditions by solving the wave equation of a sucker-rod string is the theoretical basis of a sucker-rod pumping system. To overcome the shortcomings of the conventional finite difference method and analytical solution, this work describes a novel hybrid method that combines the analytical solution with the finite difference method. In this method, an analytical solution of the tapered rod wave equation with a recursive matrix form based on the Fourier series is proposed, a unified pumping condition model is established, a modified finite difference method is given, a hybrid strategy is established, and a convergence calculation method is proposed. Based on two different types of oil wells, the analytical solutions are verified by comparing different methods. The hybrid method is verified by using the finite difference method simulated data and measured oil data. The pumping speed sensitivity and convergence of the hybrid method are studied. The results show that the proposed analytical solution has high accuracy, with a maximum relative error relative to that of the classical finite difference method of 0.062%. The proposed hybrid method has a high simulation accuracy, with a maximum relative area error relative to that of the finite difference method of 0.09% and a maximum relative area error relative to measured data of 1.89%. Even at higher pumping speeds, the hybrid method still has accuracy. The hybrid method in this paper is convergent. The introduction of the finite difference method allows the hybrid method to more easily converge. The novelty of this work is that it combines the advantages of the finite difference method and the analytical solution, and it provides a convergence calculation method to provide guidance for its application. The hybrid method presented in this paper provides an alternative scheme for predicting the behavior of sucker-rod pumping systems and a new approach for solving wave equations with complex boundary conditions. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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14 pages, 3882 KiB

Open AccessArticle

Numerical Solutions of Second-Order Elliptic Equations with C-Bézier Basis

by Lanyin Sun, Fangming Su and Kunkun Pang

Axioms 2024, 13(2), 84; https://doi.org/10.3390/axioms13020084 - 27 Jan 2024

Viewed by 1215

Abstract

This article introduces a finite element method based on the C-Bézier basis function for second-order elliptic equations. The trial function of the finite element method is set up using a combination of C-Bézier tensor product bases. One advantage of the C-Bézier basis is [...] Read more.

This article introduces a finite element method based on the C-Bézier basis function for second-order elliptic equations. The trial function of the finite element method is set up using a combination of C-Bézier tensor product bases. One advantage of the C-Bézier basis is that it has a free shape parameter, which makes geometric modeling more convenience and flexible. The performance of the C-Bézier basis is searched for by studying three test examples. The numerical results demonstrate that this method is able to provide more accurate numerical approximations than the classical Lagrange basis. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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12 pages, 561 KiB

Open AccessArticle

A Steady-State-Preserving Numerical Scheme for One-Dimensional Blood Flow Model

by Carlos A. Vega, Sonia Valbuena and Jesús Blanco Bojato

Mathematics 2024, 12(3), 407; https://doi.org/10.3390/math12030407 - 26 Jan 2024

Viewed by 1105

Abstract

In this work, an entropy-stable and well-balanced numerical scheme for a one-dimensional blood flow model is presented. Such a scheme was obtained from an explicit entropy-conservative flux along with a second-order discretisation of the source term by using centred finite differences. We prove [...] Read more.

In this work, an entropy-stable and well-balanced numerical scheme for a one-dimensional blood flow model is presented. Such a scheme was obtained from an explicit entropy-conservative flux along with a second-order discretisation of the source term by using centred finite differences. We prove that the scheme is entropy-stable and preserves steady-state solutions. In addition, some numerical examples are included to test the performance of the proposed scheme. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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20 pages, 1458 KiB

Open AccessArticle

Modified Characteristic Finite Element Method with Second-Order Spatial Accuracy for Solving Convection-Dominated Problem on Surfaces

by Longyuan Wu, Xinlong Feng and Yinnian He

Entropy 2023, 25(12), 1631; https://doi.org/10.3390/e25121631 - 7 Dec 2023

Viewed by 1328

Abstract

We present a modified characteristic finite element method that exhibits second-order spatial accuracy for solving convection–reaction–diffusion equations on surfaces. The temporal direction adopted the backward-Euler method, while the spatial direction employed the surface finite element method. In contrast to regular domains, it is [...] Read more.

We present a modified characteristic finite element method that exhibits second-order spatial accuracy for solving convection–reaction–diffusion equations on surfaces. The temporal direction adopted the backward-Euler method, while the spatial direction employed the surface finite element method. In contrast to regular domains, it is observed that the point in the characteristic direction traverses the surface only once within a brief time. Thus, good approximation of the solution in the characteristic direction holds significant importance for the numerical scheme. In this regard, Taylor expansion is employed to reconstruct the solution beyond the surface in the characteristic direction. The stability of our scheme is then proved. A comparison is carried out with an existing characteristic finite element method based on face mesh. Numerical examples are provided to validate the effectiveness of our proposed method. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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21 pages, 2571 KiB

Open AccessArticle

An Efficient Method for Solving Two-Dimensional Partial Differential Equations with the Deep Operator Network

by Xiaoyu Zhang, Yichao Wang, Xiting Peng and Chaofeng Zhang

Axioms 2023, 12(12), 1095; https://doi.org/10.3390/axioms12121095 - 29 Nov 2023

Viewed by 2510

Abstract

Partial differential equations (PDEs) usually apply for modeling complex physical phenomena in the real world, and the corresponding solution is the key to interpreting these problems. Generally, traditional solving methods suffer from inefficiency and time consumption. At the same time, the current rise [...] Read more.

Partial differential equations (PDEs) usually apply for modeling complex physical phenomena in the real world, and the corresponding solution is the key to interpreting these problems. Generally, traditional solving methods suffer from inefficiency and time consumption. At the same time, the current rise in machine learning algorithms, represented by the Deep Operator Network (DeepONet), could compensate for these shortcomings and effectively predict the solutions of PDEs by learning the operators from the data. The current deep learning-based methods focus on solving one-dimensional PDEs, but the research on higher-dimensional problems is still in development. Therefore, this paper proposes an efficient scheme to predict the solution of two-dimensional PDEs with improved DeepONet. In order to construct the data needed for training, the functions are sampled from a classical function space and produce the corresponding two-dimensional data. The difference method is used to obtain the numerical solutions of the PDEs and form a point-value data set. For training the network, the matrix representing two-dimensional functions is processed to form vectors and adapt the DeepONet model perfectly. In addition, we theoretically prove that the discrete point division of the data ensures that the model loss is guaranteed to be in a small range. This method is verified for predicting the two-dimensional Poisson equation and heat conduction equation solutions through experiments. Compared with other methods, the proposed scheme is simple and effective. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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13 pages, 6415 KiB

Open AccessArticle

High-Performance Computational Method for an Extended Three-Coupled Korteweg–de Vries System

by Panpan Wang and Xiufang Feng

Axioms 2023, 12(10), 990; https://doi.org/10.3390/axioms12100990 - 19 Oct 2023

Cited by 1 | Viewed by 1334

Abstract

This paper calculates numerical solutions of an extended three-coupled Korteweg–de Vries system by the q-homotopy analysis transformation method (q-HATM), which is a hybrid of the Laplace transform and the q-homotopy analysis method. Multiple investigations inspecting planetary oceans, optical cables, and cosmic plasma have [...] Read more.

This paper calculates numerical solutions of an extended three-coupled Korteweg–de Vries system by the q-homotopy analysis transformation method (q-HATM), which is a hybrid of the Laplace transform and the q-homotopy analysis method. Multiple investigations inspecting planetary oceans, optical cables, and cosmic plasma have employed the KdV model, significantly contributing to its development. The uniqueness, convergence, and maximum absolute truncation error of this algorithm are demonstrated. A numerical simulation has been performed to validate the accuracy and validity of the proposed approach. With high accuracy and few algorithmic processes, this algorithm supplies a series solution in the form of a recursive relation. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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15 pages, 5254 KiB

Open AccessEditor’s ChoiceArticle

Applying Physics-Informed Neural Networks to Solve Navier–Stokes Equations for Laminar Flow around a Particle

by Beichao Hu and Dwayne McDaniel

Math. Comput. Appl. 2023, 28(5), 102; https://doi.org/10.3390/mca28050102 - 13 Oct 2023

Cited by 6 | Viewed by 5746

Abstract

In recent years, Physics-Informed Neural Networks (PINNs) have drawn great interest among researchers as a tool to solve computational physics problems. Unlike conventional neural networks, which are black-box models that “blindly” establish a correlation between input and output variables using a large quantity [...] Read more.

In recent years, Physics-Informed Neural Networks (PINNs) have drawn great interest among researchers as a tool to solve computational physics problems. Unlike conventional neural networks, which are black-box models that “blindly” establish a correlation between input and output variables using a large quantity of labeled data, PINNs directly embed physical laws (primarily partial differential equations) within the loss function of neural networks. By minimizing the loss function, this approach allows the output variables to automatically satisfy physical equations without the need for labeled data. The Navier–Stokes equation is one of the most classic governing equations in thermal fluid engineering. This study constructs a PINN to solve the Navier–Stokes equations for a 2D incompressible laminar flow problem. Flows passing around a 2D circular particle are chosen as the benchmark case, and an elliptical particle is also examined to enrich the research. The velocity and pressure fields are predicted by the PINNs, and the results are compared with those derived from Computational Fluid Dynamics (CFD). Additionally, the particle drag force coefficient is calculated to quantify the discrepancy in the results of the PINNs as compared to CFD outcomes. The drag coefficient maintained an error within 10% across all test scenarios. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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15 pages, 299 KiB

Open AccessArticle

Convergence Analysis of the Strang Splitting Method for the Degasperis-Procesi Equation

by Runjie Zhang and Jinwei Fang

Axioms 2023, 12(10), 946; https://doi.org/10.3390/axioms12100946 - 4 Oct 2023

Viewed by 1276

Abstract

This article is concerned with the convergence properties of the Strang splitting method for the Degasperis-Procesi equation, which models shallow water dynamics. The challenges of analyzing splitting methods for this equation lie in the fact that the involved suboperators are both nonlinear. In [...] Read more.

This article is concerned with the convergence properties of the Strang splitting method for the Degasperis-Procesi equation, which models shallow water dynamics. The challenges of analyzing splitting methods for this equation lie in the fact that the involved suboperators are both nonlinear. In this paper, instead of building the second order convergence in

L^{2}

for the proposed method directly, we first show that the Strang splitting method has first order convergence in

H^{2}

. In the analysis, the Lie derivative bounds for the local errors are crucial. The obtained first order convergence result provides the

H^{2}

boundedness of the approximate solutions, thereby enabling us to subsequently establish the second order convergence in

L^{2}

for the Strang splitting method. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

17 pages, 14521 KiB

Open AccessArticle

A Boundary-Type Numerical Procedure to Solve Nonlinear Nonhomogeneous Backward-in-Time Heat Conduction Equations

by Yung-Wei Chen, Jian-Hung Shen, Yen-Shen Chang and Chun-Ming Chang

Mathematics 2023, 11(19), 4052; https://doi.org/10.3390/math11194052 - 24 Sep 2023

Viewed by 1177

Abstract

In this paper, an explicit boundary-type numerical procedure, including a constraint-type fictitious time integration method (FTIM) and a two-point boundary solution of the Lie-group shooting method (LGSM), is constructed to tackle nonlinear nonhomogeneous backward heat conduction problems (BHCPs). Conventional methods cannot effectively overcome [...] Read more.

In this paper, an explicit boundary-type numerical procedure, including a constraint-type fictitious time integration method (FTIM) and a two-point boundary solution of the Lie-group shooting method (LGSM), is constructed to tackle nonlinear nonhomogeneous backward heat conduction problems (BHCPs). Conventional methods cannot effectively overcome numerical instability to solve inverse problems that lack initial conditions and take a long time to calculate, even using different variable transformations and regularization techniques. Therefore, an explicit-type numerical procedure is developed from the FTIM and the LGSM to avoid numerical instability and numerical iterations. First, a two-point boundary solution of the LGSM is introduced into the numerical algorithm. Then, the maximum and minimum values of the initial guess value can be determined linearly from the boundary conditions at the initial and final times. Finally, an explicit-type boundary-type numerical procedure, including a boundary value solution and constraint-type FTIM, can directly avoid the numerical iterative problems of BHCPs. Several nonlinear examples are tested. Based on the numerical results shown, this boundary-type numerical procedure using a two-point solution can directly obtain an approximated solution and can achieve stable convergence to boundary conditions, even if numerical iterations occur. Furthermore, the numerical efficiency and accuracy are better than in the previous literature, even with an increased computational time span without the regularization technique. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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16 pages, 6724 KiB

Open AccessArticle

Efficient Numerical Simulation of Biochemotaxis Phenomena in Fluid Environments

by Xingying Zhou, Guoqing Bian, Yan Wang and Xufeng Xiao

Entropy 2023, 25(8), 1224; https://doi.org/10.3390/e25081224 - 17 Aug 2023

Cited by 1 | Viewed by 1489

Abstract

A novel dimension splitting method is proposed for the efficient numerical simulation of a biochemotaxis model, which is a coupled system of chemotaxis–fluid equations and incompressible Navier–Stokes equations. A second-order pressure correction method is employed to decouple the velocity and pressure for the [...] Read more.

A novel dimension splitting method is proposed for the efficient numerical simulation of a biochemotaxis model, which is a coupled system of chemotaxis–fluid equations and incompressible Navier–Stokes equations. A second-order pressure correction method is employed to decouple the velocity and pressure for the Navier–Stokes equations. Then, the alternating direction implicit scheme is used to solve the velocity equation, and the operator with dimension splitting effect is used instead of the traditional elliptic operator to solve the pressure equation. For the chemotactic equation, the operator splitting method and extrapolation technique are used to solve oxygen and cell density to achieve second-order time accuracy. The proposed dimension splitting method splits the two-dimensional problem into a one-dimensional problem by splitting the spatial derivative, which reduces the computation and storage costs. Finally, through interesting experiments, we show the evolution of the cell plume shape during the descent process. The effect of changing specific parameters on the velocity and plume shape during the descent process is also studied. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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11 pages, 3951 KiB

Open AccessArticle

M-WDRNNs: Mixed-Weighted Deep Residual Neural Networks for Forward and Inverse PDE Problems

by Jiachun Zheng and Yunlei Yang

Axioms 2023, 12(8), 750; https://doi.org/10.3390/axioms12080750 - 30 Jul 2023

Cited by 1 | Viewed by 1686

Abstract

Physics-informed neural networks (PINNs) have been widely used to solve partial differential equations in recent years. But studies have shown that there is a gradient pathology in PINNs. That is, there is an imbalance gradient problem in each regularization term during back-propagation, which [...] Read more.

Physics-informed neural networks (PINNs) have been widely used to solve partial differential equations in recent years. But studies have shown that there is a gradient pathology in PINNs. That is, there is an imbalance gradient problem in each regularization term during back-propagation, which makes it difficult for neural network models to accurately approximate partial differential equations. Based on the depth-weighted residual neural network and neural attention mechanism, we propose a new mixed-weighted residual block in which the weighted coefficients are chosen autonomously by the optimization algorithm, and one of the transformer networks is replaced by a skip connection. Finally, we test our algorithms with some partial differential equations, such as the non-homogeneous Klein–Gordon equation, the (1+1) advection–diffusion equation, and the Helmholtz equation. Experimental results show that the proposed algorithm significantly improves the numerical accuracy. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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14 pages, 294 KiB

Open AccessArticle

Stability of Stochastic Partial Differential Equations

by Allaberen Ashyralyev and Ülker Okur

Axioms 2023, 12(7), 718; https://doi.org/10.3390/axioms12070718 - 24 Jul 2023

Cited by 1 | Viewed by 1382

Abstract

In this paper, we study the stability of the stochastic parabolic differential equation with dependent coefficients. We consider the stability of an abstract Cauchy problem for the solution of certain stochastic parabolic differential equations in a Hilbert space. For the solution of the [...] Read more.

In this paper, we study the stability of the stochastic parabolic differential equation with dependent coefficients. We consider the stability of an abstract Cauchy problem for the solution of certain stochastic parabolic differential equations in a Hilbert space. For the solution of the initial-boundary value problems (IBVPs), we obtain the stability estimates for stochastic parabolic equations with dependent coefficients in specific applications. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

29 pages, 4347 KiB

Open AccessArticle

Higher-Order Blended Compact Difference Scheme on Nonuniform Grids for the 3D Steady Convection-Diffusion Equation

by Tingfu Ma, Bin Lan, Yongbin Ge and Lili Wu

Axioms 2023, 12(7), 651; https://doi.org/10.3390/axioms12070651 - 29 Jun 2023

Viewed by 1280

Abstract

This paper proposes a higher-order blended compact difference (BCD) scheme on nonuniform grids for solving the three-dimensional (3D) convection–diffusion equation with variable coefficients. The BCD scheme has fifth- to sixth-order accuracy and considers the first and second derivatives of the unknown function as [...] Read more.

This paper proposes a higher-order blended compact difference (BCD) scheme on nonuniform grids for solving the three-dimensional (3D) convection–diffusion equation with variable coefficients. The BCD scheme has fifth- to sixth-order accuracy and considers the first and second derivatives of the unknown function as unknowns as well. Unlike other schemes that require grid transformation, the BCD scheme does not require any grid transformation and is simple and flexible in grid subdivisions. Concurrently, the corresponding high-order boundary schemes of the first and second derivatives have also been constructed. We tested the BCD scheme on three problems that involve convection-dominated and boundary-layer features. The numerical results show that the BCD scheme has good adaptability and high resolution on nonuniform grids. It outperforms the BCD scheme on uniform grids and the high-order compact scheme on nonuniform grids in the literature in terms of accuracy and resolution. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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15 pages, 683 KiB

Open AccessArticle

Finite Element Error Analysis of a Viscoelastic Timoshenko Beam with Thermodiffusion Effects

by Jacobo G. Baldonedo, José R. Fernández, Abraham Segade and Sofía Suárez

Mathematics 2023, 11(13), 2900; https://doi.org/10.3390/math11132900 - 28 Jun 2023

Viewed by 1247

Abstract

In this paper, a thermomechanical problem involving a viscoelastic Timoshenko beam is analyzed from a numerical point of view. The so-called thermodiffusion effects are also included in the model. The problem is written as a linear system composed of two second-order-in-time partial differential [...] Read more.

In this paper, a thermomechanical problem involving a viscoelastic Timoshenko beam is analyzed from a numerical point of view. The so-called thermodiffusion effects are also included in the model. The problem is written as a linear system composed of two second-order-in-time partial differential equations for the transverse displacement and the rotational movement, and two first-order-in-time partial differential equations for the temperature and the chemical potential. The corresponding variational formulation leads to a coupled system of first-order linear variational equations written in terms of the transverse velocity, the rotation speed, the temperature and the chemical potential. The existence and uniqueness of solutions, as well as the energy decay property, are stated. Then, we focus on the numerical approximation of this weak problem by using the implicit Euler scheme to discretize the time derivatives and the classical finite element method to approximate the spatial variable. A discrete stability property and some a priori error estimates are shown, from which we can conclude the linear convergence of the approximations under suitable additional regularity conditions. Finally, some numerical simulations are performed to demonstrate the accuracy of the scheme, the behavior of the discrete energy decay and the dependence of the solution with respect to some parameters. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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12 pages, 2771 KiB

Open AccessArticle

Solve High-Dimensional Reflected Partial Differential Equations by Neural Network Method

by Xiaowen Shi, Xiangyu Zhang, Renwu Tang and Juan Yang

Math. Comput. Appl. 2023, 28(4), 79; https://doi.org/10.3390/mca28040079 - 24 Jun 2023

Viewed by 2104

Abstract

Reflected partial differential equations (PDEs) have important applications in financial mathematics, stochastic control, physics, and engineering. This paper aims to present a numerical method for solving high-dimensional reflected PDEs. In fact, overcoming the “dimensional curse” and approximating the reflection term are challenges. Some [...] Read more.

Reflected partial differential equations (PDEs) have important applications in financial mathematics, stochastic control, physics, and engineering. This paper aims to present a numerical method for solving high-dimensional reflected PDEs. In fact, overcoming the “dimensional curse” and approximating the reflection term are challenges. Some numerical algorithms based on neural networks developed recently fail in solving high-dimensional reflected PDEs. To solve these problems, firstly, the reflected PDEs are transformed into reflected backward stochastic differential equations (BSDEs) using the reflected Feyman–Kac formula. Secondly, the reflection term of the reflected BSDEs is approximated using the penalization method. Next, the BSDEs are discretized using a strategy that combines Euler and Crank–Nicolson schemes. Finally, a deep neural network model is employed to simulate the solution of the BSDEs. The effectiveness of the proposed method is tested by two numerical experiments, and the model shows high stability and accuracy in solving reflected PDEs of up to 100 dimensions. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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18 pages, 2778 KiB

Open AccessArticle

Urban Heat Island Dynamics in an Urban–Rural Domain with Variable Porosity: Numerical Methodology and Simulation

by Néstor García-Chan, Juan A. Licea-Salazar and Luis G. Gutierrez-Ibarra

Mathematics 2023, 11(5), 1140; https://doi.org/10.3390/math11051140 - 24 Feb 2023

Cited by 5 | Viewed by 2539

Abstract

Heat transfer and fluid dynamics modeling in porous media is a widely explored topic in physics and applied mathematics, and it involves advanced numerical methods to address its non-linear nature. One interesting application has been the urban-heat-island (UHI) numerical simulation. The UHI is [...] Read more.

Heat transfer and fluid dynamics modeling in porous media is a widely explored topic in physics and applied mathematics, and it involves advanced numerical methods to address its non-linear nature. One interesting application has been the urban-heat-island (UHI) numerical simulation. The UHI is a negative consequence of the increasing urbanization in cities, which is defined as the presence of warm temperatures inside the urban canopy in contrast to the colder surroundings. Furthermore, an interesting phenomena occurs within a UHI context when the city transitions from a heat island to a cold island, matching the increases and decreases of solar radiation over the span of a day, as well as the decrease in the UHI intensity as a result of wind action. The numerical study in this paper had, as its main goal, to reproduce this phenomenon. Therefore, the key elements proposed in this work were the following: A 2D horizontal urban–rural domain that had a variable porosity with a Gaussian distribution centered in the city center. A non-stationary Darcy–Forchheimer–Brinkman model to simulate the flow in porous media, combined with an air–soil heat transport model linked by a balancing equation for the surface energy that includes the evapotranspiration of plants. In regards to the numerical resolution of the model, a classical numerical methodology based on the finite elements of Lagrange P₁ type combined with explicit and implicit time-marching schemes have been effective for high-quality numerical simulations. Several numerical tests were performed on a domain inspired by the metropolitan region of Guadalajara (Mexico), in which not only the temperature inversion was reproduced but also the simulation of the UHI transition by strong wind gusts. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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25 pages, 6144 KiB

Open AccessArticle

Finite Difference Method to Evaluate the Characteristics of Optically Dense Gray Nanofluid Heat Transfer around the Surface of a Sphere and in the Plume Region

by Muhammad Ashraf, Anwar Khan, Amir Abbas, Abid Hussanan, Kaouther Ghachem, Chemseddine Maatki and Lioua Kolsi

Mathematics 2023, 11(4), 908; https://doi.org/10.3390/math11040908 - 10 Feb 2023

Cited by 28 | Viewed by 2183

Abstract

The current research study is focusing on the investigation of the physical effects of thermal radiation on heat and mass transfer of a nanofluid located around a sphere. The configuration is investigated by solving the partial differential equations governing the phenomenon. By using [...] Read more.

The current research study is focusing on the investigation of the physical effects of thermal radiation on heat and mass transfer of a nanofluid located around a sphere. The configuration is investigated by solving the partial differential equations governing the phenomenon. By using suitable non-dimensional variables, the governing set of partial differential equations is transformed into a dimensionless form. For numerical simulation, the attained set of dimensionless partial differential equations is discretized by using the finite difference method. The effects of the governing parameters, such as the Brownian motion parameter, the thermophoresis parameter, the radiation parameter, the Prandtl number, and the Schmidt number on the velocity field, temperature distribution, and mass concentration, are presented graphically. Moreover, the impacts of these physical parameters on the skin friction coefficient, the Nusselt number, and the Sherwood number are displayed in the form of tables. Numerical outcomes reflect that the effects of the radiation parameter, thermophoresis parameter, and the Brownian motion parameter intensify the profiles of velocity, temperature, and concentration at different circumferential positions on the sphere. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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17 pages, 2503 KiB

Open AccessArticle

A Finite Volume Method to Solve the Ill-Posed Elliptic Problems

by Ying Sheng and Tie Zhang

Mathematics 2022, 10(22), 4220; https://doi.org/10.3390/math10224220 - 11 Nov 2022

Cited by 3 | Viewed by 1587

Abstract

In this paper, we propose a finite volume element method of primal-dual type to solve the ill-posed elliptic problem, that is, the elliptic problem with lacking or overlapping boundary value condition. We first establish the primal-dual finite volume element scheme by introducing the [...] Read more.

In this paper, we propose a finite volume element method of primal-dual type to solve the ill-posed elliptic problem, that is, the elliptic problem with lacking or overlapping boundary value condition. We first establish the primal-dual finite volume element scheme by introducing the Lagrange multiplier

λ

and prove the well-posedness of the discrete scheme. Then, the error estimations of the finite volume solution are derived under some proper norms including the

H^{1}

-norm. Numerical experiments are provided to verify the effectiveness of the proposed finite volume element method at last. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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13 pages, 1288 KiB

Open AccessArticle

An Unchanged Basis Function and Preserving Accuracy Crank–Nicolson Finite Element Reduced-Dimension Method for Symmetric Tempered Fractional Diffusion Equation

by Xiaoyong Yang and Zhendong Luo

Mathematics 2022, 10(19), 3630; https://doi.org/10.3390/math10193630 - 4 Oct 2022

Cited by 4 | Viewed by 1602

Abstract

We herein mainly employ a proper orthogonal decomposition (POD) to study the reduced dimension of unknown solution coefficient vectors in the Crank–Nicolson finite element (FE) (CNFE) method for the symmetric tempered fractional diffusion equation so that we can build the reduced-dimension recursive CNFE [...] Read more.

We herein mainly employ a proper orthogonal decomposition (POD) to study the reduced dimension of unknown solution coefficient vectors in the Crank–Nicolson finite element (FE) (CNFE) method for the symmetric tempered fractional diffusion equation so that we can build the reduced-dimension recursive CNFE (RDRCNFE) method. In this case, the RDRCNFE method keeps the same basic functions and accuracy as the CNFE method. Especially, we adopt the matrix analysis to discuss the stability and convergence of RDRCNFE solutions, resulting in the very laconic theoretical analysis. We also use some numerical simulations to confirm the correctness of theoretical results. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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17 pages, 4364 KiB

Open AccessArticle

A Modular Grad-Div Stabilization Method for Time-Dependent Thermally Coupled MHD Equations

by Xianzhu Li and Haiyan Su

Entropy 2022, 24(10), 1336; https://doi.org/10.3390/e24101336 - 22 Sep 2022

Cited by 3 | Viewed by 2031

Abstract

In this paper, we consider a fully discrete modular grad-div stabilization algorithm for time-dependent thermally coupled magnetohydrodynamic (MHD) equations. The main idea of the proposed algorithm is to add an extra minimally intrusive module to penalize the divergence errors of velocity and improve [...] Read more.

In this paper, we consider a fully discrete modular grad-div stabilization algorithm for time-dependent thermally coupled magnetohydrodynamic (MHD) equations. The main idea of the proposed algorithm is to add an extra minimally intrusive module to penalize the divergence errors of velocity and improve the computational efficiency for increasing values of the Reynolds number and grad-div stabilization parameters. In addition, we provide the unconditional stability and optimal convergence analysis of this algorithm. Finally, several numerical experiments are performed and further indicated these advantages over the algorithm without grad-div stabilization. Full article

(This article belongs to the Topic Numerical Methods for Partial Differential Equations)

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