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Numerical Methods for Partial Differential Equations最新文献

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Double diffusive effects on nanofluid flow toward a permeable stretching surface in presence of Thermophoresis and Brownian motion effects: A numerical study 热泳效应和布朗运动效应对纳米流体流向可渗透拉伸表面的双重扩散效应:数值研究
IF 3.9 3区 数学 Q1 Mathematics Pub Date : 2024-01-19 DOI: 10.1002/num.23086
V. V. L. Deepthi, V. K. Narla, R. Srinivasa Raju
The present study explores the nanofluid boundary layer flow over a stretching sheet with the combined influence of the double diffusive effects of thermophoresis and Brownian motion effects. For the purpose of transforming nonlinear partial differential equations into the linear united ordinary differential equation method, the similarity transformation technique is used. The Runge–Kutta–Fehlberg method was used to solve the equations of flow, along with sufficient boundary conditions. The effect on hydrodynamic, thermal and solutes boundary layers of a number of related parameters is investigated and the effects are graphically displayed. In conclusion, a strong agreement between the current numerical findings and the previous literature results is sought.
本研究探讨了在热泳效应和布朗运动效应双重扩散效应共同影响下拉伸片上的纳米流体边界层流动。为了将非线性偏微分方程转换为线性联合常微分方程方法,采用了相似性转换技术。采用 Runge-Kutta-Fehlberg 方法求解流动方程,并充分考虑了边界条件。研究了一些相关参数对流体力学、热学和溶质边界层的影响,并以图形显示了这些影响。总之,目前的数值研究结果与之前的文献结果非常吻合。
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引用次数: 0
Improved error estimates of the time-splitting methods for the long-time dynamics of the Klein–Gordon–Dirac system with the small coupling constant 具有小耦合常数的克莱因-戈登-狄拉克系统长时动力学时间分割方法的改进误差估计
IF 3.9 3区 数学 Q1 Mathematics Pub Date : 2023-12-11 DOI: 10.1002/num.23084
Jiyong Li
We provide improved uniform error estimates for the time-splitting Fourier pseudo-spectral (TSFP) methods applied to the Klein–Gordon–Dirac system (KGDS) with the small parameter
我们为应用于具有小参数◂+▸ε∈(0,1]$$ varepsilon in left(0,1right] $$$的Klein-Gordon-Dirac系统(KGDS)的时间分裂傅立叶伪谱(TSFP)方法提供了改进的均匀误差估计。我们首先将 KGDS 重述为耦合薛定谔-狄拉克系统(CSDS),然后将二阶斯特朗分裂法应用于 CSDS,并用傅立叶伪谱法提供空间离散化。基于严格的分析、我们建立了二阶斯特朗分裂法在 O◂()▸(◂◽˙▸hm-1+ετ2)$$ Oleft({h}^{m-1}+varepsilon {tau}^2right) $$ 直到 ◂⋅▸O(1/ε)$$ Oleft(1/varepsilon right) $$ 的长时。除常规分析方法外,我们主要应用正则补偿振荡技术进行长时间动态模拟分析。数值结果表明,我们的方法和结论不仅适用于一维问题,而且可以直接扩展到高维问题和高振荡问题。据我们所知,目前还没有针对求解 KGDS 的 TSFP 方法的相关长时间分析和改进的均匀误差边界。我们的方法很新颖,为分析类似 KGDS 的其他耦合系统的改进误差边界提供了参考。
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引用次数: 0
Robust finite element methods and solvers for the Biot–Brinkman equations in vorticity form 涡量型Biot-Brinkman方程的鲁棒有限元方法及求解方法
IF 3.9 3区 数学 Q1 Mathematics Pub Date : 2023-11-27 DOI: 10.1002/num.23083
Ruben Caraballo, Chansophea Wathanak In, Alberto F. Martín, Ricardo Ruiz-Baier
In this article, we propose a new formulation and a suitable finite element method for the steady coupling of viscous flow in deformable porous media using divergence-conforming filtration fluxes. The proposed method is based on the use of parameter-weighted spaces, which allows for a more accurate and robust analysis of the continuous and discrete problems. Furthermore, we conduct a solvability analysis of the proposed method and derive optimal error estimates in appropriate norms. These error estimates are shown to be robust in a variety of regimes, including the case of large Lamé parameters and small permeability and storativity coefficients. To illustrate the effectiveness of the proposed method, we provide a few representative numerical examples, including convergence verification and testing of robustness of block-diagonal preconditioners with respect to model parameters.
在本文中,我们提出了一种新的公式和合适的有限元方法来计算可变形多孔介质中粘性流动的稳态耦合。该方法基于参数加权空间的使用,可以对连续和离散问题进行更准确和鲁棒的分析。此外,我们对所提出的方法进行了可解性分析,并在适当的规范下得出了最优误差估计。这些误差估计在各种情况下都具有鲁棒性,包括在lam参数大、渗透率和存储系数小的情况下。为了说明所提方法的有效性,我们提供了几个有代表性的数值例子,包括收敛性验证和块对角预调节器相对于模型参数的鲁棒性测试。
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引用次数: 0
Iteration acceleration methods for solving three-temperature heat conduction equations on distorted meshes 变形网格上三温热传导方程的迭代加速求解方法
IF 3.9 3区 数学 Q1 Mathematics Pub Date : 2023-11-27 DOI: 10.1002/num.23085
Yunlong Yu, Xingding Chen, Yanzhong Yao
This article focuses on designing efficient iteration algorithms for nonequilibrium three-temperature heat conduction equations, which are used to formulate the radiative energy transport problem. Based on the framework of relaxation iteration, we design a new accelerated iteration algorithm by reasonable approximation of the Jacobi matrix, according to the characteristics of the discrete scheme for the three-temperature equations. Adopting the iteration framework, we analyze the advantages and disadvantages of several iteration algorithms commonly used in practice and the new iteration algorithm. Finally, we compare the new iteration algorithm with some other iteration algorithms by solving several nonlinear models, and show that the new algorithm can achieve significant acceleration effect.
本文重点研究了求解非平衡态三温热传导方程的高效迭代算法,该算法用于求解辐射能量输运问题。根据三温方程离散格式的特点,在松弛迭代框架下,通过合理逼近雅可比矩阵,设计了一种新的加速迭代算法。采用迭代框架,分析了实践中常用的几种迭代算法和新的迭代算法的优缺点。最后,通过求解多个非线性模型,将新迭代算法与其他迭代算法进行了比较,结果表明新算法可以取得显著的加速效果。
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引用次数: 0
A radial basis function (RBF)-finite difference method for solving improved Boussinesq model with error estimation and description of solitary waves 径向基函数-有限差分法求解具有误差估计和孤立波描述的改进Boussinesq模型
IF 3.9 3区 数学 Q1 Mathematics Pub Date : 2023-11-15 DOI: 10.1002/num.23077
Mostafa Abbaszadeh, AliReza Bagheri Salec, Taghreed Abdul-Kareem Hatim Aal-Ezirej
The Boussinesq equation has some application in fluid dynamics, water sciences and so forth. In the current paper, we study an improved Boussinesq model. First, a finite difference approximation is employed to discrete the derivative of the temporal variable. Then, we study the existence and uniqueness of solution of the semi-discrete scheme according to the fixed point theorem. In addition, the unconditional stability and convergence of the semi-discrete scheme are presented. Then, we construct the fully discrete formulation based upon the radial basis function-finite difference method. The convergence rate and stability of the fully-discrete scheme are analyzed. In the end, some examples in 1D and 2D cases are studied to corroborate the capability of the proposed scheme.
Boussinesq方程在流体力学、水科学等方面有一定的应用。本文研究了一种改进的Boussinesq模型。首先,采用有限差分近似对时间变量的导数进行离散。然后,根据不动点定理,研究了半离散格式解的存在唯一性。此外,还给出了半离散格式的无条件稳定性和收敛性。然后,基于径向基函数-有限差分法构造了全离散公式。分析了全离散格式的收敛速度和稳定性。最后,通过一维和二维实例验证了所提方案的有效性。
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引用次数: 0
Efficient and accurate temporal second-order numerical methods for multidimensional multi-term integrodifferential equations with the Abel kernels 具有阿贝尔核的多维多项积分微分方程的有效和精确的时间二阶数值方法
IF 3.9 3区 数学 Q1 Mathematics Pub Date : 2023-11-14 DOI: 10.1002/num.23082
Mingchao Zhao, Hao Chen, Kexin Li
This work develops two temporal second-order alternating direction implicit (ADI) numerical schemes for solving multidimensional parabolic-type integrodifferential equations with multi-term weakly singular Abel kernels. For the two-dimensional (2D) case, applying the Crank–Nicolson method and product integration rule to discretizations of temporal derivative and integral terms, respectively, and the spatial discretization is proposed using a compact difference formulation combined with the ADI algorithm; for the three-dimensional case, the method of temporal discretization is the same as the 2D case, and then we employ the standard finite difference in space to construct a fully discrete ADI finite difference scheme. The ADI technique is used to reduce the calculation cost of the high-dimensional problem. Besides, the stability and convergence of two ADI schemes are rigorously proved by the energy argument, in which the first scheme converges to the order τ2+h14+h24�$$ {tau}^2+{h}_1^4+{h}_2^4 $$�, where τ�$$ tau $$�, h1�$$ {h}_1 $$�, and h2�$$ {h}_2 $$� denote the time-space step sizes, respectively, and the second scheme converges to the space-time second-order accuracy. Finally, the numerical results verify the correctness of the theoretical analysis and show that the method of this article is competitive with the existing research work.
本文给出了求解具有多项弱奇异阿贝尔核的多维抛物型积分微分方程的两种时间二阶交替方向隐式数值格式。对于二维(2D)情况,分别采用Crank-Nicolson方法和积积分规则对时间导数项和积分项进行离散化,并采用紧凑差分公式结合ADI算法对空间进行离散化;对于三维情况,采用与二维情况相同的时间离散化方法,然后利用空间上的标准有限差分构造一个完全离散的ADI有限差分格式。采用ADI技术降低了高维问题的计算成本。此外,通过能量论证严格证明了两种ADI格式的稳定性和收敛性,其中第一种格式收敛于τ2+h14+h24 $$ {tau}^2+{h}_1^4+{h}_2^4 $$阶,其中τ $$ tau $$、h1 $$ {h}_1 $$和h2 $$ {h}_2 $$分别表示时空步长,第二种格式收敛于时空二阶精度。最后,数值结果验证了理论分析的正确性,表明本文方法与已有的研究工作相比具有一定的竞争力。
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引用次数: 0
Unfitted generalized finite element methods for Dirichlet problems without penalty or stabilization 无惩罚或稳定Dirichlet问题的非拟合广义有限元方法
3区 数学 Q1 Mathematics Pub Date : 2023-11-09 DOI: 10.1002/num.23081
Qinghui Zhang
Abstract Unfitted finite element methods (FEM) have attractive merits for problems with evolving or geometrically complex boundaries. Conventional unfitted FEMs incorporate penalty terms, parameters, or Lagrange multipliers to impose the Dirichlet boundary condition weakly. This to some extent increases computational complexity in implementation. In this article, we propose an unfitted generalized FEM (GFEM) for the Dirichlet problem, which is free from any penalty or stabilization. This is achieved by means of partition of unity frameworks of GFEM and designing a set of new enrichments for the Dirichlet boundary. The enrichments are divided into two groups: the one is used to impose the Dirichlet boundary condition strongly, and the other one serves as energy space of variational formulations. The shape functions in energy space vanish at the boundary so that standard variational formulae like those in the conventional fitted FEM can be applied, and thus the penalty and stabilization are not needed. The optimal convergence rate in the energy norm is proven rigorously. Numerical experiments and comparisons with other methods are executed to verify the theoretical result and effectiveness of the algorithm. The conditioning of new method is numerically shown to be of same order as that of the standard FEM.
非拟合有限元法(FEM)对于具有演化边界或几何复杂边界的问题具有吸引人的优点。传统的非拟合fem采用惩罚项、参数或拉格朗日乘子来弱地施加狄利克雷边界条件。这在一定程度上增加了实现中的计算复杂性。本文针对Dirichlet问题,提出了一种不存在任何惩罚和镇定的非拟合广义有限元(GFEM)。这是通过划分GFEM的统一框架和设计一组新的Dirichlet边界富集来实现的。富集可分为两组:一组用于强施加Dirichlet边界条件,另一组用作变分公式的能量空间。能量空间的形状函数在边界处消失,可以采用传统的拟合有限元中的标准变分公式,从而不需要惩罚和稳定化。严格证明了能量范数下的最优收敛速度。通过数值实验和与其他方法的比较,验证了该算法的理论结果和有效性。数值结果表明,新方法的条件与标准有限元法的条件相同。
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引用次数: 0
Numerical approximation for hybrid‐dimensional flow and transport in fractured porous media 裂隙多孔介质中混合维流动和输运的数值近似
3区 数学 Q1 Mathematics Pub Date : 2023-11-05 DOI: 10.1002/num.23080
Jijing Zhao, Hongxing Rui
Abstract This article presents the stable miscible displacement problem in fractured porous media, and finite element discretization is constructed for this reduced model. The transmission interface conditions presented in this article enable us to derive a stability result and conduct the case where the pressure and concentration are both discontinuous across the fracture. The error estimates for and norm are established under the assumption of regular solutions. We perform some numerical examples to verify the theoretical analysis. Last, some unsteady physical experiments, more realistic test cases, are presented to prove the validity of the model and method.
摘要本文提出了裂缝性多孔介质中稳定混相驱替问题,并对该简化模型进行了有限元离散化处理。本文提出的传输界面条件使我们能够得出稳定性结果,并进行压力和浓度在裂缝上均不连续的情况。在正则解的假设下,建立了误差估计和范数。通过算例验证了理论分析的正确性。最后,给出了一些非定常物理实验和较为实际的测试用例,验证了模型和方法的有效性。
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引用次数: 0
Numerical algorithm with fifth‐order accuracy for axisymmetric Laplace equation with linear boundary value problem 线性边值问题轴对称拉普拉斯方程的五阶精度数值算法
3区 数学 Q1 Mathematics Pub Date : 2023-10-30 DOI: 10.1002/num.23079
Hu Li, Jin Huang
Abstract In order to obtain the numerical solutions of the axisymmetric Laplace equation with linear boundary problem in three dimensions, we have developed a quadrature method to solve the problem. Firstly, the problem can be transformed to a integral equation with weakly singular operator by using the Green's formula. Secondly, A quadrature method is constructed by combing the mid‐rectangle formula with a singular integral formula to solve the integral equation, which has the accuracy of and low computational complexity. Thirdly, the convergence of the numerical solutions is proved based on the theory of compact operators and the single parameter asymptotic expansion of errors with odd power is got. From the expansion, we construct an extrapolation algorithm (EA) to further improve the accuracy of the numerical solutions. After one extrapolation, the accuracy of the numerical solutions can reach the accuracy of . Finally, two numerical examples are presented to demonstrate the efficiency of the method.
摘要为了在三维空间中得到具有线性边界问题的轴对称拉普拉斯方程的数值解,提出了求解该问题的正交法。首先,利用格林公式将问题转化为具有弱奇异算子的积分方程。其次,将中矩形公式与奇异积分公式相结合,构造了求解积分方程的正交法,该方法具有精度高、计算量小的优点。第三,利用紧算子理论证明了数值解的收敛性,得到了误差的奇次单参数渐近展开式。在此基础上,构造了外推算法(EA),进一步提高了数值解的精度。外推一次后,数值解的精度可达到。最后给出了两个数值算例,验证了该方法的有效性。
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引用次数: 0
Error analyses on block‐centered finite difference schemes for distributed‐order non‐Fickian flow 分布阶非菲克流块中心有限差分格式的误差分析
3区 数学 Q1 Mathematics Pub Date : 2023-10-24 DOI: 10.1002/num.23078
Xuan Zhao, Ziyan Li
Abstract In this article, two numerical schemes are designed and analyzed for the distributed‐order non‐Fickian flow. Two different processing techniques are applied to deal with the time distributed‐order derivative for the constructed two schemes, while the classical block‐centered finite difference method is used in spatial discretization. To be precise, one adopts the standard numerical scheme called SD scheme in the temporal direction, and the other utilizes an efficient method called EF scheme. We derive the stabilities of the two schemes rigorously. The convergence result of the SD scheme for pressure and velocity is . However, to get a faster computing speed, the super parameter is needed for the EF scheme, which leads to the accuracy is . Finally, some numerical experiments are carried out to verify the theoretical analysis.
摘要本文设计并分析了分布阶非菲克流的两种数值格式。对于所构建的两种格式,采用了两种不同的处理技术来处理时间分布阶导数,而在空间离散化中则使用了经典的块中心有限差分方法。准确地说,一种是在时间方向上采用标准的数值格式SD格式,另一种是采用一种高效的方法EF格式。我们严格地推导了这两种方案的稳定性。压力和速度SD格式的收敛结果为。然而,为了获得更快的计算速度,EF格式需要超参数,导致精度为。最后通过数值实验验证了理论分析的正确性。
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引用次数: 0
期刊
Numerical Methods for Partial Differential Equations
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