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A kernel compensation mimetic difference scheme for the grad-div eigenvalue problem 梯度特征值问题的核补偿拟差分格式
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-04 DOI: 10.1016/j.camwa.2025.11.015
Chenyang Wang, Yan Xu
We propose a kernel compensation mimetic difference (MD) scheme to solve the grad-div eigenvalue problem. This method utilizes a curl-curl type compensation operator along with carefully selected boundary conditions to effectively manage the infinite-dimensional kernel of the grad-div operator. To ensure high accuracy, we apply stencil-based MD operators to discretize the grad-div operator under Dirichlet boundary conditions. This results in a numerical scheme characterized by a sparse stiff matrix with a narrow bandwidth while achieving high-order accuracy. We construct the compensation operator with a proper boundary condition that is orthogonal to the discrete grad-div operator. A generalized identification method for spurious eigenvalues is presented. The resulting scheme offers several advantages, including high-order accuracy, enhanced computational efficiency with reduced memory usage, and excellent scalability for parallel computation. Numerical tests demonstrate that our approach not only converges at the expected rates but also performs satisfactorily in terms of speed.
针对梯度特征值问题,提出了一种核补偿模拟差分(MD)方案。该方法利用旋旋型补偿算子和精心选择的边界条件,有效地管理了梯度算子的无限维核。为了保证高精度,我们在Dirichlet边界条件下,采用基于模板的MD算子对梯度算子进行离散化。这使得该数值格式具有窄带宽的稀疏刚性矩阵的特点,同时又能获得高阶精度。构造了具有与离散梯度-div算子正交的适当边界条件的补偿算子。提出了一种伪特征值的广义辨识方法。由此产生的方案具有几个优点,包括高阶精度、通过减少内存使用提高计算效率以及并行计算的出色可伸缩性。数值测试表明,该方法不仅能达到预期的收敛速度,而且在速度方面也有令人满意的表现。
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引用次数: 0
Geometry-independent spline boundary element method to analyze three-dimensional potential and elasticity problems 几何无关样条边界元法分析三维位势和弹性问题
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-24 DOI: 10.1016/j.camwa.2025.12.014
Jiaxing Chen, Lei Wang, Jiawei Xiang
In research on the integration of computer-aided design (CAD) and numerical simulations of boundary types, commonly used methods for constructing approximate functions include non-uniform rational B-splines (NURBS) interpolation and moving least-squares (MLS) interpolation. These methods struggle to precisely enforce boundary conditions due to the lack of Kronecker delta properties in their shape functions. To address this limitation, this paper proposes a geometry-independent spline boundary element method (GISBEM) that introduces a transformation matrix to construct a spline interpolation function as the shape function, enabling direct application of boundary conditions akin to the boundary element method (BEM). First, the concept of geometry-independent field approximation (GIFT) is introduced, where the geometry is accurately described by NURBS, and the field variables of the elements are approximated using B-spline interpolation and transformation matrices. Second, the computation formats for the 3D potential and elasticity problems are derived using parameter mapping. Third, the calculation of variables at the boundary points is performed on the element using the relationship between the variables, with subsequent processing similar to that of BEM. Finally, the effectiveness and accuracy of the proposed method are verified through numerical examples.
在计算机辅助设计(CAD)与边界类型数值模拟相结合的研究中,常用的近似函数构造方法有非均匀有理b样条(NURBS)插值法和移动最小二乘(MLS)插值法。这些方法很难精确地执行边界条件,因为在它们的形状函数中缺乏Kronecker delta特性。为了解决这一限制,本文提出了一种与几何无关的样条边界元方法(GISBEM),该方法引入了一个变换矩阵来构造样条插值函数作为形状函数,从而可以直接应用类似于边界元方法(BEM)的边界条件。首先,引入了与几何无关的场近似(GIFT)概念,利用NURBS精确描述几何形状,利用b样条插值和变换矩阵逼近单元的场变量;其次,利用参数映射法推导了三维位势和弹性问题的计算格式。第三,利用变量之间的关系对单元进行边界点处变量的计算,后续处理类似于边界元法。最后,通过数值算例验证了所提方法的有效性和准确性。
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引用次数: 0
The mechanism analysis for the fractional quantum dynamics on a comb structure with the absorbing boundary conditions 具有吸收边界条件的梳状结构分数阶量子动力学机理分析
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-24 DOI: 10.1016/j.camwa.2025.12.012
Sitao Zhang , Lin Liu , Yu Liu , Hongqing Song , Libo Feng
The paper contributes to investigating the quantum transport on a comb structure, whose feature of quantum motion is geometrically constrained such that the quantum motion is exclusively restricted to the backbone along the x-direction. Instead of substituting with the fractional derivative directly, the one-dimensional (1D) time fractional Schrödinger equation (TFSE) is formulated, which is derived by mathematical derivation from the 2D Schrödinger equation with the wave operator (SEWO). The infinite boundaries are replaced with the absorbing boundary conditions (ABCs). The finite difference method (FDM) is formulated, followed by theoretical analysis to establish stability and convergence. A fast scheme is employed to enhance computational efficiency. The contrast of the numerical and exact solutions is analyzed by innovating a source term. In addition, the contrast of the distributions for the ABCs and zero boundary conditions is analyzed. Results show that ABCs provide a more accurate numerical solution compared to zero boundary conditions. Finally, the evolutions of the modules and the phasic pictures with different parameters are given.
本文研究了量子运动特征受几何约束的梳状结构上的量子输运,这种结构的量子运动只局限于沿x方向的主干上。本文不直接代入分数阶导数,而是利用波浪算子(SEWO)对二维Schrödinger方程进行数学推导,得到一维时间分数阶Schrödinger方程。用吸收边界条件(abc)代替了无限边界。建立了有限差分法,并进行了理论分析,证明了算法的稳定性和收敛性。为了提高计算效率,采用了快速方案。通过对源项进行创新,分析了数值解与精确解的对比。此外,还对abc和零边界条件下的分布进行了对比分析。结果表明,与零边界条件相比,abc提供了更精确的数值解。最后给出了模块的演化过程和不同参数下的相位图。
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引用次数: 0
A compact difference method for the 2-D Kuramoto-Tsuzuki complex equation with Neumann boundary characterized by strong nonlinear effects 具有强非线性效应的二维具有Neumann边界的Kuramoto-Tsuzuki复方程的紧致差分法
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-04 DOI: 10.1016/j.camwa.2025.11.013
Jinxiu Zhang , Xuehua Yang , Song Wang
This paper develops and analyzes a linearized compact three-levelfinite difference (CTLFD) scheme to solve the two-dimensional (2-D) Kuramoto-Tsuzuki dynamics dominated by strong nonlinear characteristics. This method combines the compact difference method (CDM) in space with the Crank-Nicolson (C-N) scheme in time, achieving an overall convergence rate of O(τ2+hx4+hy4), where τ, hx, and hy represent the time and space step sizes, respectively. Nonlinear terms are linearized in a semi-implicit manner to enhance stability and computational efficiency. A rigorous stability and error analysis is carried out using an energy technique together with mathematical induction, confirming boundedness, uniqueness, and the optimal convergence for the numerical solution under two discrete norms. Finally, three sets of numerical experiments are presented to verify the theoretical results and demonstrate the accuracy and robustness of the proposed scheme.
本文提出并分析了一种线性化紧致三能级有限差分(CTLFD)格式,用于求解具有强非线性特征的二维Kuramoto-Tsuzuki动力学问题。该方法将空间上的紧差分法(CDM)与时间上的Crank-Nicolson (C-N)格式相结合,总体收敛速度为O(τ2+hx4+hy4),其中τ、hx和hy分别表示时间和空间步长。非线性项以半隐式方式线性化,以提高稳定性和计算效率。利用能量技术结合数学归纳法,对两离散范数下数值解的有界性、唯一性和最优收敛性进行了严格的稳定性和误差分析。最后,通过三组数值实验对理论结果进行了验证,验证了所提方案的准确性和鲁棒性。
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引用次数: 0
New solvers for coupled flow and transport on quadrilateral meshes: Property-preserving and optimal-order convergence 四边形网格上流动和输运耦合的新解:保性质和最优阶收敛
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-08 DOI: 10.1016/j.camwa.2025.11.014
Boyang Yu , Yonghai Li , Jiangguo Liu
This paper develops two novel numerical solvers on quadrilateral meshes for coupled flow and transport problems. The focus is placed on preserving physical properties such as mass conservation and concentration positivity. Quadrilateral meshes are used due to their flexibility in accommodation of domain geometry. A weak Galerkin (WG) finite element scheme with linear shape functions is utilized to solve the Darcy equation. Mapped bilinear finite volumes on the same mesh are then used to solve the time-dependent convection-diffusion equation, which rely on the numerical velocity obtained from the Darcy scheme. Techniques for positivity-correction are applied to both diffusive and convective fluxes. Global mass conservation, positivity-preserving, and optimal order convergence are carefully examined under appropriate conditions. Numerical tests demonstrate robustness of our new solvers in handling convection dominance and anisotropy/heterogeneity in permeability and/or diffusion.
本文提出了两种新的四边形网格流动与输运耦合问题的数值求解方法。重点是保持物理性质,如质量守恒和浓度正性。由于四边形网格在适应区域几何结构方面具有灵活性,因此采用四边形网格。采用线性形函数的弱伽辽金(WG)有限元格式求解达西方程。然后在同一网格上映射双线性有限体积来求解依赖于Darcy格式的数值速度的随时间的对流扩散方程。正校正技术适用于扩散通量和对流通量。在适当的条件下,仔细检查了全局质量守恒,正守恒和最优阶收敛。数值测试证明了我们的新求解器在处理对流优势和渗透率和/或扩散的各向异性/非均质性方面的鲁棒性。
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引用次数: 0
Mathematical modeling of myocardial perfusion using lattice Boltzmann method 用晶格玻尔兹曼方法建立心肌灌注的数学模型
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2026-01-08 DOI: 10.1016/j.camwa.2025.12.005
Jan Kovář , Radek Fučík , Tarique Hussain , Munes Fares , Radomír Chabiniok
We propose a two-compartment mathematical model of myocardial perfusion, representing myocardial tissue at the arteriolar level. The model comprises a simplified two-dimensional geometrical analog of the complex three-dimensional myocardial vasculature. In the advective compartment, consisting of a 2D vasculature analog, fluid flow and contrast agent transport are governed by Navier-Stokes and system of advection-diffusion equations, respectively. The surrounding myocardium, included in porous capillary compartment and modeled as a porous medium, assumes purely diffusive transport without fluid flow. Contrast agent exchange occurs through the interface between the two compartments. The model is numerically solved using the lattice Boltzmann method, with GPU implementation enabling massive parallelization. Sample contrast agent profiles are analyzed for both healthy and defective tissues. The model’s capability to interpret actual MRI perfusion curves is evaluated using mathematical optimization techniques. Furthermore, the model is employed for a binary classification test to evaluate its agreement with the expert opinion of a qualified clinician. Myocardial blood flow approximations from the proposed model compare favorably to results from established medical software utilizing signal-deconvolution methods. Despite its simplifications, the 2D model accurately represents essential perfusion dynamics, matching or exceeding clinical software in agreement with expert evaluations. Although tested on a small number of patients, this proof of concept shows potential for direct application during perfusion exams or generating synthetic data for machine learning.
我们提出了心肌灌注的两室数学模型,代表心肌组织在小动脉水平。该模型包含复杂的三维心肌血管系统的简化二维几何模拟。在由二维脉管系统模拟组成的平流室中,流体流动和造影剂运输分别由Navier-Stokes方程和平流-扩散方程系统控制。周围的心肌,包括在多孔毛细血管室中,并模拟为多孔介质,假设纯扩散运输,没有流体流动。造影剂的交换通过两个隔室之间的界面进行。该模型采用晶格玻尔兹曼方法进行数值求解,GPU实现实现了大规模并行化。样本造影剂配置文件分析为健康和缺陷组织。该模型解释实际MRI灌注曲线的能力使用数学优化技术进行评估。此外,将该模型用于二元分类检验,以评估其与合格临床医生的专家意见的一致性。所提出的模型的心肌血流量近似与利用信号反卷积方法建立的医疗软件的结果相比较有利。尽管其简化,二维模型准确地表示基本灌注动力学,匹配或超过临床软件与专家的评估一致。尽管在少数患者身上进行了测试,但这一概念证明显示了在灌注检查或为机器学习生成合成数据时直接应用的潜力。
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引用次数: 0
Quadrature error estimates for kernels with logarithmic singularity 具有对数奇异性核的正交误差估计
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-08 DOI: 10.1016/j.camwa.2025.11.022
Ismail Labaali , Maria Rosaria Lancia , Chiara Sorgentone
Boundary integral methods are a powerful tool to solve partial differential equations by reformulating them as integral equations over the boundary of the domain. When dealing with boundary integral methods, and in particular with the numerical integration of layer potentials, it is essential to estimate the magnitude of the error associated with the underlying quadrature rule. As the evaluation point approaches the boundary, the integral becomes nearly-singular and the associated quadrature error increases rapidly. Being able to estimate such error is needed to identify when the accuracy becomes inadequate, and the use of a specialized quadrature method is required. In this work we provide accurate quadrature error estimates for the Gauss-Legendre and the trapezoidal rules in computing two-dimensional layer potentials with logarithmic singularities.
边界积分法是求解偏微分方程的有力工具,它将偏微分方程重新表述为域边界上的积分方程。在处理边界积分方法时,特别是处理层势的数值积分时,估计与基本正交规则相关的误差的大小是必要的。当计算点接近边界时,积分近似奇异,积分误差迅速增大。当精度不足时,需要能够估计这种误差来识别,并且需要使用专门的正交方法。在这项工作中,我们提供了精确的正交误差估计高斯-勒让德规则和梯形规则在计算具有对数奇点的二维层势。
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引用次数: 0
An efficient reduced-order approximation for the stochastic Allen-Cahn equation 随机Allen-Cahn方程的有效降阶近似
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-05 DOI: 10.1016/j.camwa.2025.11.019
Xiao Qi , Yubin Yan
In this paper, we propose and analyze an efficient numerical method for solving the stochastic Allen-Cahn equation with additive noise. The method combines a stabilized semi-implicit time discretization scheme with a reduced-order finite element spatial discretization method. The core idea is to approximate the original high-dimensional solution space via a low-dimensional subspace, constructed by the Proper Orthogonal Decomposition (POD) method based on an ensemble of snapshots from the full-order model at selected time instances. First, we rigorously establish the spatio-temporal strong convergence rates between the mild solution and the reduced-order solution. Second, in large-sample simulations, the reduced-order basis exhibits a certain generalization capability in capturing the average behavior of the numerical solutions. Numerical experiments are provided to verify the theoretical error estimates and to demonstrate the effectiveness of the proposed method.
本文提出并分析了一种求解具有加性噪声的随机Allen-Cahn方程的有效数值方法。该方法将稳定的半隐式时间离散方法与降阶有限元空间离散方法相结合。其核心思想是通过低维子空间来近似原始高维解空间,该子空间是基于全阶模型在选定时间实例上的快照集合,通过适当正交分解(POD)方法构造的。首先,我们严格地建立了温和解和降阶解之间的时空强收敛速率。其次,在大样本模拟中,降阶基在捕获数值解的平均行为方面表现出一定的泛化能力。数值实验验证了理论误差估计,并证明了所提方法的有效性。
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引用次数: 0
Two-stage fourth-order Hermite weighted compact nonlinear scheme for hyperbolic conservation laws 双曲型守恒律的两阶段四阶Hermite加权紧非线性格式
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-10 DOI: 10.1016/j.camwa.2025.11.026
Weihao Xie , Zhifang Du , Guangxue Wang , Huaibao Zhang
In this work, we propose a fifth-order Hermite weighted compact nonlinear scheme (HWCNS) within the framework of the two-stage fourth-order Lax-Wendroff-type time discretization by Li and Du (SIAM J Sci Comput 38 (5):A3046-A3069, 2016). Unlike the traditional weighted compact nonlinear scheme (WCNS), which uses the Runge-Kutta method for high-order temporal integration, and solves only for nodal values, this new HWCNS simultaneously evolves both nodal and midpoint values within the same time discretization. These solutions are then used to compute first-order spatial derivatives at the nodes. By incorporating both nodal values and their derivatives, the scheme enables a high-order nonlinear Hermite interpolation. Furthermore, we introduce a “polynomial stencil selection procedure” derived from the targeted essentially non-oscillatory (TENO) scheme to improve the performance of the nonlinear interpolation. A variety of benchmark cases are addressed in one- and two-dimensional dimensions. The proposed scheme, based on the Lax-Wendroff time discretization, exhibits promising characteristics of minimal dissipation and dispersion errors for fine-scale features in smooth flow regions, and demonstrates robust shock-capturing capabilities with high resolutions, benefiting from its compact stencil in both time and space. Moreover, integration of the TENO technique into the nonlinear interpolation yields a further reduction in numerical dissipation, as shown in the numerical tests.
本文在Li和Du的两阶段四阶lax - wendroff型时间离散化框架内提出了一种五阶Hermite加权紧化非线性格式(HWCNS) (SIAM J .计算机学报,38 (5):A3046-A3069, 2016)。与传统加权紧化非线性格式(WCNS)采用龙格-库塔方法进行高阶时间积分,只求解节点值不同,该算法在同一时间离散化过程中同时演化节点和中点值。然后使用这些解来计算节点上的一阶空间导数。通过结合节点值及其导数,该方案实现了高阶非线性埃尔米特插值。此外,我们引入了一种“多项式模板选择程序”,该程序源于目标基本非振荡(TENO)方案,以提高非线性插值的性能。在一维和二维维度中处理各种基准测试案例。该方法基于Lax-Wendroff时间离散化,在光滑流动区域具有最小耗散和最小色散误差的特点,并具有高分辨率的强大激波捕获能力,这得益于其紧凑的时间和空间模板。此外,如数值试验所示,将TENO技术集成到非线性插值中可以进一步减少数值耗散。
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引用次数: 0
Numerical analysis of the second-order fully discrete schemes for parabolic problem based on serendipity virtual element method 基于偶然性虚元法的抛物型问题二阶全离散格式的数值分析
IF 2.5 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-02-01 Epub Date: 2025-12-10 DOI: 10.1016/j.camwa.2025.11.016
Jianjun Wan, Yuanjiang Xu, Jiaxin Wei, Shilei Xu, Chunyan Niu
In this paper, the Crank-Nicolson and BDF2 schemes, based on the serendipity virtual element method, are applied to solve parabolic problems. The main content of this article is to analyze the fully discrete error in zero and energy norm for these two second-order fully discrete schemes and to conduct numerical experiments. We derive optimal zero and energy norm error estimates for the Crank-Nicolson and BDF2 schemes. In addition, the errors in zero norm and energy norm of the semi-discrete scheme of serendipity virtual elements are estimated. Through numerical experiments conducted on rectangular, convex polygonal, and non-convex polygonal meshes, discrete errors are presented in the spatial and temporal directions, respectively. Finally, we demonstrated the computational complexity advantage of serendipity virtual elements by calculating the total degrees of freedom.
本文采用基于偶然性虚元法的Crank-Nicolson格式和BDF2格式求解抛物型问题。本文的主要内容是分析这两种二阶全离散格式的全离散零点误差和能量范数,并进行数值实验。我们得到了Crank-Nicolson和BDF2格式的最优零和能量范数误差估计。此外,对偶然性虚元半离散格式的零范数和能量范数误差进行了估计。通过对矩形、凸多边形和非凸多边形网格的数值实验,分别在空间和时间方向上呈现离散误差。最后,通过对总自由度的计算,证明了偶然性虚拟元素在计算复杂度上的优势。
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引用次数: 0
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Computers & Mathematics with Applications
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