Article
Computer Science, Interdisciplinary Applications
Xixian Bai, Hongxing Rui
Summary: A fully implicit finite-difference time-domain (FDTD) scheme with second-order space-time accuracy for Maxwell's equations in a Cole-Cole dispersive medium is proposed and analyzed. The proposed scheme is rigorously analyzed and shown to be unconditionally stable with second-order accuracy in both time and space. Numerical examples are provided to validate the theoretical findings.
ENGINEERING WITH COMPUTERS
(2022)
Article
Computer Science, Interdisciplinary Applications
Theodoros T. Zygiridis, Aristeides D. Papadopoulos, Nikolaos Kantartzis
Summary: This paper presents a design procedure for FDTD algorithms based on the (2,4) stencil, which achieve reduced error levels in problems with Lorentz dispersion. The novel finite-difference formulae for spatial derivatives show performance improvement and accuracy amendment in cases where dispersive materials need to be considered.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Piotr Pietruszka, Tomasz P. Stefanski, Jacek Gulgowski
Summary: This paper investigates the electromagnetic simulation method in media described by time-fractional constitutive relations. A discrete approximation based on the finite-difference time-domain (FDTD) method is proposed and its accuracy is validated through comparison with frequency-domain simulations. However, high spatial resolution and computationally demanding memory are required for accurate results.
APPLIED SCIENCES-BASEL
(2023)
Article
Computer Science, Interdisciplinary Applications
Revathi Jambunathan, Zhi Yao, Richard Lombardini, Aaron Rodriguez, Andrew Nonaka
Summary: In this study, a new London equation module for superconductivity is implemented in the GPU-enabled ARTEMIS framework and coupled with a finite-difference time-domain solver for Maxwell's equations. The two-fluid approach is applied to model a superconducting coplanar waveguide (CPW) resonator. The implementation is validated by obtaining the theoretical skin depth and reflection coefficients for various superconductive materials with different London penetration depths at different frequencies. The convergence studies show that the algorithm is second-order accurate in both space and time, except at superconducting interfaces where it is first-order accurate in space. In CPW simulations, the two-fluid model is compared to traditional approaches approximating superconducting behavior, demonstrating comparable performance to the assumption of quasi-infinite conductivity as measured by the Q-factor.
COMPUTER PHYSICS COMMUNICATIONS
(2023)
Article
Mathematics, Applied
Yann-Meing Law, Jean-Christophe Nave
Summary: This paper proposes high-order FDTD schemes for solving Maxwell's interface problems with discontinuous coefficients and complex interfaces, based on the Correction Function Method (CFM). The CFM is used to model the correction function near the interface and retain the accuracy of finite difference approximation. The proposed CFM-FDTD schemes achieve fourth-order convergence and provide accurate solutions devoid of spurious oscillations.
JOURNAL OF SCIENTIFIC COMPUTING
(2022)
Review
Computer Science, Information Systems
Luciano Mescia, Pietro Bia, Diego Caratelli
Summary: The use of fractional derivatives and integrals in electromagnetic theory has shown promising results in capturing effects and generalizing Maxwell's equations. In this paper, the authors provide a brief review of fractional vector calculus and its applications, focusing on dielectric relaxation processes exhibiting non-exponential decay. A homemade fractional calculus-based FDTD scheme is discussed in detail, with considerations for computational domain bounding and numerical stability. Examples involving dispersive dielectrics demonstrate the usefulness and reliability of the developed FDTD scheme.
Article
Multidisciplinary Sciences
Olaoluwa Ayodeji Jejeniwa, Hagos Hailu Gidey, Appanah Rao Appadu
Summary: In this study, three finite difference schemes were used to solve 1D and 2D convective diffusion equations. Through four numerical experiments and dispersion analysis, it was found that the Lax-Wendroff scheme was the most efficient in all cases, and the optimal value of k could minimize the errors.
Article
Mathematics, Applied
Chenxi Wang, Alina Chertock, Shumo Cui, Alexander Kurganov, Zhen Zhang
Summary: In this paper, a coupled chemotaxis-fluid system is studied to model the self-organized collective behavior of oxytactic bacteria in a sessile drop. A new positivity preserving and high-resolution method based on the diffuse-domain approach is developed to solve the chemotaxis-fluid system. Numerical experiments are performed to demonstrate the performance of the proposed approach on different shapes of sessile drops, showing interesting chemotactic phenomena.
MATHEMATICAL MODELS & METHODS IN APPLIED SCIENCES
(2023)
Article
Mathematics, Applied
Xixian Bai, Hongxing Rui
Summary: A fast and easily implemented algorithm for time fractional Maxwell's system, based on the SOE approximation and FDTD method, achieves high efficiency with no loss in accuracy as shown through numerical experiments in 2D and 3D.
APPLIED MATHEMATICS LETTERS
(2021)
Article
Mathematics, Applied
Yann-Meing Law, Jean-Christophe Nave
Summary: In this study, staggered FDTD schemes based on the correction function method (CFM) were proposed to discretize Maxwell's equations with embedded perfect electric conductor boundary conditions. The use of fictitious interfaces to fulfill the lack of information on the embedded boundary led to high-order convergence of the CFM-FDTD schemes. Stability and convergence studies were conducted using long time simulations in 2-D for various geometries of the embedded boundary.
JOURNAL OF SCIENTIFIC COMPUTING
(2021)
Article
Mathematics, Applied
Jichun Li, Li Zhu, Todd Arbogast
Summary: In this paper, a new variational form is developed to simulate the propagation of surface plasmon polaritons on graphene sheets. Graphene is treated as a thin sheet of current with an effective conductivity, and modeled as a lower-dimensional interface. A novel time-domain finite element method is proposed to solve this graphene model, which couples an ordinary differential equation on the interface with Maxwell's equations in the physical domain. Discrete stability and error estimate are proved for the proposed method. Numerical results are presented to demonstrate the effectiveness of this graphene model for simulating the surface plasmon polaritons propagating on graphene sheets.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2023)
Article
Mathematics, Applied
Weimin Han, Chenghang Song, Fei Wang, Jinghuai Gao
Summary: The paper introduces semi-discrete and fully discrete numerical methods for solving the diffusive-viscous wave equation and derives optimal error estimates. Numerical results on a test problem illustrate the numerical convergence orders.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2021)
Article
Mathematics, Applied
E. M. Elsayed, Q. Din, N. A. Bukhary
Summary: This paper obtains the form of solutions of a specific rational system of difference equations, which consists of three related equations and the initial values are non-zero real numbers.
Article
Engineering, Electrical & Electronic
Yong-Dan Kong, Xiang-Lin Chen, Qing-Xin Chu
Summary: The study systematically investigates the numerical stability and dispersion analysis of the extended 2-D finite-difference time-domain (2-D-FDTD) method. It analyzes three different passive linear lumped elements, namely resistor, inductor, and capacitor, as well as three different formulations of explicit, semi-implicit, and implicit schemes. The numerical stability is analyzed by utilizing the von Neumann technique and Jury criterion, which has not been previously reported. Theoretical results show the stability conditions for different elements and schemes, and the analysis of numerical dispersion based on the Norton equivalent circuit leads to interesting theoretical deductions.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2023)
Article
Mathematics, Applied
Asad Anees, Lutz Angermann
Summary: This study proposes novel finite element methods in the time domain to solve the system of Maxwell's equations with a cubic nonlinearity in 3D spatial cases. The methods accurately model the effects of linear and nonlinear electric polarization and achieve an energy stable discretization. The proposed time discretization scheme is unconditionally stable with respect to the electromagnetic energy and allows for discretization of complex geometries and nonlinearities in 3D problems derived from the full system of nonlinear Maxwell's equations.
INTERNATIONAL JOURNAL OF NUMERICAL ANALYSIS AND MODELING
(2022)
Article
Mathematics, Applied
Xixian Bai, Hongxing Rui
Summary: A fast and easily implemented algorithm for time fractional Maxwell's system, based on the SOE approximation and FDTD method, achieves high efficiency with no loss in accuracy as shown through numerical experiments in 2D and 3D.
APPLIED MATHEMATICS LETTERS
(2021)
Article
Mathematics, Applied
Xixian Bai, Hongxing Rui
Summary: This paper introduces new energy identities for metamaterial Maxwell's equations with PEC boundary conditions, different from the Poynting theorem. It is proved that the Yee scheme remains stable on non-uniform rectangular meshes when the CFL condition is met. Numerical experiments confirm the analysis and reveal superconvergence in the discrete H-1 norm.
ADVANCES IN APPLIED MATHEMATICS AND MECHANICS
(2021)
Article
Computer Science, Interdisciplinary Applications
Xixian Bai, Hongxing Rui
Summary: A fully implicit finite-difference time-domain (FDTD) scheme with second-order space-time accuracy for Maxwell's equations in a Cole-Cole dispersive medium is proposed and analyzed. The proposed scheme is rigorously analyzed and shown to be unconditionally stable with second-order accuracy in both time and space. Numerical examples are provided to validate the theoretical findings.
ENGINEERING WITH COMPUTERS
(2022)
Article
Mathematics, Applied
Xixian Bai, Jian Huang, Hongxing Rui, Shuang Wang
Summary: In this paper, a fast second-order finite-difference time-domain (FDTD) algorithm based on the FL2-1(sigma) formula and a weighted approach is proposed for solving the time fractional Maxwell's system. The discretization of the Caputo derivative term is constructed, and a fast second-order fully discrete FDTD algorithm is developed based on this discretization. Numerical examples with analytic solutions are provided to demonstrate the accuracy and efficiency of the proposed algorithm.
JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
(2022)
Article
Mathematics, Applied
Junfeng Cao, Ke Chen, Huan Han
Summary: This paper proposes a two-stage image segmentation model based on structure tensor and fractional-order regularization. In the first stage, fractional-order regularization is used to approximate the Hausdorff measure of the MS model. The solution is found using the ADI scheme. In the second stage, thresholding is used for target segmentation. The proposed model demonstrates superior performance compared to state-of-the-art methods.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Dylan J. Oliver, Ian W. Turner, Elliot J. Carr
Summary: This paper discusses a projection-based framework for numerical computation of advection-diffusion-reaction (ADR) equations in heterogeneous media with multiple layers or complex geometric structures. By obtaining approximate solutions on a coarse grid and reconstructing solutions on a fine grid, the computational cost is significantly reduced while accurately approximating complex solutions.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Nathan V. Roberts, Sean T. Miller, Stephen D. Bond, Eric C. Cyr
Summary: In this study, the time-marching discontinuous Petrov-Galerkin (DPG) method is applied to the Vlasov equation for the first time, using backward Euler for a Vlasov-Poisson discretization. Adaptive mesh refinement is demonstrated on two problems: the two-stream instability problem and a cold diode problem.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Yizhi Sun, Zhilin Sun
Summary: This work investigates the convexity of a specific class of positive definite probability measures and demonstrates the preservation of convexity under multiplication and intertwining product. The study reveals that any integrable function on an interval with a polynomial expansion of fast absolute convergence can be decomposed into a pair of positive convex interval probabilities, simplifying the study of interval distributions and discontinuous probabilistic Galerkin schemes.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Bhagwan Singh, Komal Jangid, Santwana Mukhopadhyay
Summary: This paper examines the prediction of bending characteristics of nanoscale materials using the Moore-Gibson-Thompson thermoelasticity theory in conjunction with the nonlocal strain gradient theory. The study finds that the stiffness of the materials can be affected by nonlocal and length-scale parameters, and the aspect ratios of the beam structure play a significant role in bending simulations.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Guoliang Wang, Bo Zheng, Yueqiang Shang
Summary: This paper presents and analyzes a parallel finite element post-processing algorithm for the simulation of Stokes equations with a nonlinear damping term, which integrates the algorithmic advantages of the two-level approach, the partition of unity method, and the post-processing technique. The algorithm generates a global continuous approximate solution using the partition of unity method and improves the smoothness of the solution by adding an extra coarse grid correction step. It has good parallel performance and is validated through theoretical error estimates and numerical test examples.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Hao Xu, Zeng-Qi Wang
Summary: Fluid flow control problems are crucial in industrial applications, and solving the optimal control of Navier-Stokes equations is challenging. By using Oseen's approximation and matrix splitting preconditioners, we can efficiently solve the linear systems and improve convergence.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)
Article
Mathematics, Applied
Zhengya Yang, Xuejuan Chen, Yanping Chen, Jing Wang
Summary: This paper focuses on the high-order stable numerical solutions of the time-space fractional diffusion equation. The Fourier spectral method is used for spatial discretization and the Spectral Deferred Correction (SDC) method is used for numerical solutions in time. As a result, a high-precision numerical discretization scheme for solving the fractional diffusion equation is obtained, and the convergence and stability of the scheme are proved. Several numerical examples are presented to demonstrate the effectiveness and feasibility of the proposed numerical scheme.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2024)