双曲-抛物型偏微分方程奇摄动混合问题的数值解法

构造了二阶双曲—抛物型方程奇摄动混合问题的差分格式，给出了差分解的能量不等式，并证明了差分解在离散范数下关于小参数一致收敛于摄动问题的解。     

二阶椭圆问题的混合元方向交替法

本文研究了一般的二阶椭圆问题的混合元方向交替法，给出了两种迭代格式即Uzawa格式和Arrow－Hurwitz格式，并就系数是常数的情形给出了谱分析．本文的结果对油藏模拟有一定的理论和实际意义．     

区域分裂法求非线性抛物方程的扩张混合元解

针对非线性抛物方程,给出了全离散的扩张混合元格式,利用一个建立在非重叠型区域分裂技巧上的并行迭代法求解了最后的非线性代数方程组,证明了迭代法的收敛性并给出了最优阶的误差估计.     

Sine-Gordon方程的混合有限体积元方法及数值模拟

研究了在Dirichlet边界条件和Neumann边界条件下一维sine-Gordon方程的混合有限体积元方法.通过引入将试探函数空间映射到检验函数空间的迁移算子γh,结合混合有限元方法和有限体积元方法,构造了半离散格式,时间显式和隐式全离散混合有限体积元格式.给出了显格式离散解的稳定性分析,并得到了三种格式的最优阶误差估计.最后,给出数值算例来验证理论分析结果和数值格式的有效性.     

多孔介质中两相不可压混溶驱替的差分流线扩散法及其误差分析

多孔介质中两相不可压混熔驱替问题可描述为椭圆和抛物耦合的非线性偏微分方程组，对椭圆方程采用混合元方法，而对抛物方程采用差分流线扩散法，本文构造了求解该问题的差分流线扩散-混合元格式，最后，给出所构造格式按L^∞(L^2）模的拟最优误差阶估计。     

多孔介质两相驱动问题的特征差分和Schwarz区域分裂并行算法

本文考虑多孔介质两相驱动问题的数值解法。用混合元方法求解压力方程，可同时得到速度和压力的近似；对浓度方程，给出了两类特征差分与Ｓｃｈｗａｒｚ型区域分裂引结合的数值格式，以减小对流项产生的数值弥散，减小所处理问题的规模和实行并行计算。     

抛物型方程的一种高精度区域分解有限差分算法

1引言 近年来,区域分解算法以可以将大型问题分解为一系列小型问题以减少计算规模及算法可高度并行实现等特点受到了人们的广泛关注.前人也做了很多很好的工作:参考文献[1]中C.N.Dawson等人提出了显一隐格式的区域分解算法,在时间层不分层的内边界点采用大步长向前-中心差分显格式及在内点采用古典隐格式,取得的精度为O(△t+h2+H3).参考文献[2]中给出了[1]中区域分解算法对于内边界点为等距分布的多子区域时的新的误差估计,使含H3误差项的系数比[1]中缩小了一倍.还将采用大步长日的saul'yev的非对称差分格式应用于内边界点,并给出了两个子区域和多个子区域情形下差分解的先验误差估计.     

热传导方程的均匀化方程的混合元方法

用混合有限元方法讨论稳态热传导问题的均匀化方程.给出了一种矩形剖分下的混合元格式,该格式具有各向异性特征,即剖分不满足正则性条件时也收敛,应用各向异性插值定理给出了误差分析.     

不可压混溶驱替问题的流线扩散──混合元数值模拟

采用标准元模拟不可压混溶流问题，当扩散系数矩阵小过剖分参数时，有限元格式仅能给出比最优精度低一阶的逼近解，格式稳定性差并伴有强烈的数值弥散现象．为了克服上述缺陷，本文对压力方程采用混合元，而对浓度方程采用流线扩散格式，在扩散矩阵为线性的假定下，证明了该格式具有较标准元更高的逼近精度（比最优阶低1／2）和更好的稳定性．     

一个新的非常规各向异性元的收敛性分析

构造了一个新的非常规各向异性Hermite型矩形单元并据此对二阶椭圆问题提出了一个混合元格式,同时给出了该格式的收敛性分析.     

Parallel domain decomposition procedures of improved D-D type for parabolic problems

Two parallel domain decomposition procedures for solving initial-boundary value problems of parabolic partial differential equations are proposed. One is the extended D-D type algorithm, which extends the explicit/implicit conservative Galerkin domain decomposition procedures, given in [5], from a rectangle domain and its decomposition that consisted of a stripe of sub-rectangles into a general domain and its general decomposition with a net-like structure. An almost optimal error estimate, without the factor H^−1/2 given in Dawson-Dupont’s error estimate, is proved. Another is the parallel domain decomposition algorithm of improved D-D type, in which an additional term is introduced to produce an approximation of an optimal error accuracy in L²-norm.     

Theory and Application of Characteristic Finite Element Domain Decomposition Procedures for Coupled System of Dynamics of Fluids in Porous Media

For a coupled system of multiplayer dynamics of fluids in porous media,the characteristic finiteelement domain decomposition procedures applicable to parallel arithmetic are put forward.Techniques suchas calculus of variations,domain decomposition,characteristic method,negative norm estimate,energy methodand the theory of prior estimates are adopted.Optimal order estimates in L~2 norm are derived for the error inthe approximate solution.     

三维两相渗流驱动问题迎风区域分裂显隐差分法

对三维两相渗流驱动问题提出了两种迎风区域分裂显隐差分格式．压力方程采用了七点差分格式,为了能达到实际并行计算的要求,对饱和度方程采用了迎风区域分裂差分法,内边界处和各子区域分别对应显隐格式．得到了离散l2模收敛性分析,最后给出数值试验,支撑了理论分析结果．     

Global and domain-decomposed mixed methods for the solution of Maxwell's equations with application to magnetotellurics

A collection of global and domain decomposition mixed finite element schemes for the approximate solution of the harmonic Maxwell's equations on a bounded domain with absorbing boundary conditions at the artificial boundaries are presented. The numerical procedures allow us to solve efficiently the direct problem in magnetotellurics consisting of determining the electromagnetic scattered field in a two–dimensional earth model of arbitrary conductivity properties. Convergence results for the numerical procedures are derived. © 1998 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 14: 407–437, 1998     

结构三角网上抛物方程的有限差分区域分解算法

1引言对于大型科学与工程计算问题,并行计算是必需的．构造高效率的数值并行方法一直是人们关心的问题,并且已有了大量的研究．在三层交替计算方法的研究中出现了许多既具有明显并行性又绝对稳定的差分格式(见[1]-[5])．在只涉及两个时间层的算法研究中,Dawson等人(见[6])首先发展了求解一维热传导方程的区域分解算法,并将其推广到     

Parallel Galerkin domain decomposition procedures for wave equation

Parallel Galerkin domain decomposition procedures for wave equation are given. These procedures use implicit method in the sub-domains and simple explicit flux calculation on the inter-boundaries of sub-domains by integral mean method or extrapolation method. Thus, the parallelism can be achieved by these procedures. The explicit nature of the flux prediction induces a time step constraint that is necessary to preserve the stability. L²-norm error estimates are derived for these procedures. Experimental results are presented to confirm the theoretical results.     

The modified method of characteristics with mixed finite element domain decomposition procedures for the transient behavior of a semiconductor device

For the transient behavior of a semiconductor device, the modified method of characteristics with mixed finite element domain decomposition procedures applicable to parallel arithmetic is put forward. The electric potential equation is described by the mixed finite element method, and the electric, hole concentration and heat conduction equations are treated by the modified method of characteristics finite element domain decomposition methods. Some techniques, such as calculus of variations, domain decomposition, characteristic method, energy method, negative norm estimate and prior estimates and techniques are employed. Optimal order estimates in L² norm are derived for the error in the approximation solution. Thus the well‐known theoretical problem has been thoroughly and completely solved.© 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 28: 353–368 2012     

Non-overlapping Domain Decomposition Method for a Nodal Finite Element Method

A new approach is proposed for constructing nonoverlapping domain decomposition procedures for solving a linear system related to a nodal finite element method. It applies to problems involving either positive semi-definite or complex indefinite local matrices. The main feature of the method is to preserve the continuity requirements on the unknowns and the finite element equations at the nodes shared by more than two subdomains and to suitably augment the local matrices. We prove that the corresponding algorithm can be seen as a converging iterative method for solving the finite element system and that it cannot break down. Each iteration is obtained by solving uncoupled local finite element systems posed in each subdomain and, in contrast to a strict domain decomposition method, is completed by solving a linear system whose unknowns are the degrees of freedom attached to the above special nodes.     

对流扩散方程区域分裂特征差分方法

1引言对流扩散方程是许多物理问题的数学模型,研究其稳定的数值解法具有重要的应用价值．而标准的差分法和有限元法通常会失效,出现数值振荡．80年代,Douglas和Russel提出了特征线方法,在一定程度上克服了数值振荡,保证了数值的稳定,尤其对“对流占优”问题,更能突出特征法的优越性,并有了大量的理论成果[1,2,3]．区域分裂是一种解决大规模的科学与工程计算问题的有效方法,Dawson,Du和Dupont对热传导方程给出了非重叠区域分裂格式及分析,由于内边界的显格式,需要一定的稳定性条件Δt≤CH2;而Du等在[5]给出了抛物方程的几种区域分裂格式,对区域分裂法的     

Parallel Galerkin domain decomposition procedures for parabolic equation on general domain

Parallel Galerkin domain decomposition procedures for parabolic equation on general domain are given. These procedures use implicit Galerkin method in the subdomains and simple explicit flux calculation on the interdomain boundaries by integral mean method or extrapolation method to predict the inner‐boundary conditions. Thus, the parallelism can be achieved by these procedures. These procedures are conservative both in the subdomains and across interboundaries. The explicit nature of the flux prediction induces a time‐step limitation that is necessary to preserve stability, but this constraint is less severe than that for a fully explicit method. L²‐norm error estimates are derived for these procedures. Compared with the work of Dawson and Dupont [Math Comp 58 (1992), 21–35], these L²‐norm error estimates avoid the loss of H^?1/2 factor. Experimental results are presented to confirm the theoretical results. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009