具体描述
内容简介
Finite Element Method and its Applications discusses the methods in a general frame and the performance on the computer, the variational formulations for elliptic boundary value problems, the error estimates and convergence for finite element approximate solutions and nonstandard finite element. In particular, presentations of the subject include the applications of finite element method to various scientific and engineering problems, for example, three dimensional elastic beam, elastic mechanics, three dimensional neutron diffusion problems, magneto hydrodynamics, three dimensional turbomachinery flows, Navier-Stokes equations and bifurcation phenomena for nonlinear problem, etc. Most applications results were established by the authors in the past three decades. This book was written by Kaitai Li, Aixiang Huang, Qinghuai Huang.
目录
Chapter 1 The Structure of Finite Element Method1.1 Galerkin Variational Principle and Ritz Variational Principle1.2 Galerkin Approximation Solution1.3 Finite Element Subspace1.4 Element Stiffness and Total Stiffness
Chapter 2 Elements and Shape Functions2.1 Rectangular Shape Function2.1.1 Lagrange Type Shape Function of Rectangular2.1.2 Hermite Type Shape Function of Rectangular2.2 Triangular Element2.2.1 Area Coordinate and Volume Coordinate2.2.2 Lagrange Type Shape Function of Triangular Element2.2.3 Hermite Type Shape Function of Triangular Element2.3 Shape Function of Three Dimensional Element2.3.1 Lagrange Type Shape Function of Hexahedron Element2.3.2 Lagrange Type Shape Function of Tetrahedron Element2.3.3 Shape Function of The Three Prism Element2.3.4 Hermite-Type Shape Function of Tetrahedron Element2.4 Iso-parametric Finite Element2.5 Curve Element
Chapter 3 Procedure and Performance of Computation of Finite Element Method3.1 The Procedure of Finite Element Computation3.2 One dimensional Store of Symmetric and Band Matrix3.3 Numerical Integration3.4 Computation of Element Stiffness Matrix and Synthesis of Total Stiffness Matrix3.4.1 Computation of Shape Function3.4.2 The Computation of Element Stiffness Matrix and Element Array3.4.3 Superposition of Elements of Total Stiffness Matrix3.5 Direct Solution Method for Finite Element Algebraic Equations3.5.1 Decomposition for Symmetric and Positive Definition Matrix3.5.2 Direct Solution for Algebraic equations3.6 Other Solution Method for Finite Element Algebraic Equations3.6.1 The Steepest Descent Method3.6.2 Conjugate Gradient Method3.7 Treatment of Constraint Conditions3.7.1 Treatment of Imposed Constraint Conditions3.7.2 Treatment of Periodic Constrain Condition3.7.3 Remove Periodic Constrain and Matrix Transformation3.7.4 Performance of the Method on Computer3.8 Calculation of Derivatives of Function3.9 Automatic Generation of Finite Element Mesh
Chapter 4 Sobolev Space4.1 Some Notations and Assumptions on Domain4.2 Classical Function Spaces4.3 LP(Ω) Space4.4 Spaces of Distribution4.5 Sobolev Spaces with Integer Index4.6 Sobolev Space with a Real Index HσP(Ω)4.7 Embedding Theorem and Interpolate Inequalities4.8 The Trace Spaces
Chapter 5 The Variational Principle for Elliptic Boundary Value Problem and Error Estimate of Finite Element Approximation Solution.5.1 Elliptic Boundary Value Problem5.1.1 Regularity5.1.2 The Existence and Uniqueness of the Solution5.1.3 Maximum Principle5.2 Variational Formulations5.3 Finite Element Approximation Solutions5.4 Coordinate Transformation and Equivalent Finite Element5.4.1 Affine Transformation and Affine Equivalent Finite Element5.4.2 Isoparametric Transformation and Isopavametric Finite Element5.5 The Theory of Finite Element Interpolation5.5.1 Some Lemma……Chapter 6 Nonstandard Finite Element MethodsChapter 7 Applications of Finite Element Method in the EngineeringChapter 8 Finite Element Analysis for Internal Flow in TurbomachineChapter 9 Finite Element Approximation for the Navier-Stokes EquationsReferences 精彩书摘
Chapter 1
The Structure of Finite Element Method
The finite element method is a numerical computational method for differential equations and partial differential equations. In order to solve the general field problem by using finite element method, it must pass through the following processes:
1) Find the variational formulation associated with original field problem.
2) Establish finite element subspace. For example, select the element type and associated phase functions.
3) Establish element stiffness matrix, element column and assemble global stiffness matrixfull column.
4) Treatment of the boundary conditions and solving of the system of finite element equations.
5) Come back to the real world. In this book, the first four processes will be systematic formulations in the first chapter till third chapter.
1.1 Galerkin Variational Principle and Ritz Variational Principle As an example, we consider the linear elliptic boundary value problem of two dimension,
(1.1.1) where, Ω is a connected domain in R2, .Ω = Γ1 ∪ Γ2 is a piecewise smooth boundary. Letn denote the unit outward normal vector to .Ω defined almost everywhere on .Ω. p(x, y) ∈C1(Ω), p(x, y) ≥ p0 > 0, σ(x, y) ∈ C0(Ω) and σ(x, y) ≥ 0.
Throughout this chapter we make notation: C0(Ω) = the set of all continuous function in an open subset in Rn. Ck(Ω) = the set of functions v ∈ C0(Ω), whose derivatives of order k,exist and are continuous;
where α = (α1, ? ? ? , αn), |α| = α1 + ? ? ? + αn.
Assume that u(x, y) ∈ C2(Ω) satisfies (1.1.1) in Ω and on .Ω, the function u(x, y) is called classical solution of problem (1.1.1).Next, we consider weak solution of (1.1.1). Define the norm
(1.1.2) Sobolev space H1(Ω) is a closure of C∞(Ω), under the norm (1.1.2) with the inner product
(1.1.3) H1(Ω) is a Hilbert space which is called one order Sobolev space. Let C∞0 (Ω) = {v : v is an infinite differentiable function and support of v . Ω}, H10 (Ω) = the closure of C∞0 (Ω) under the norm(1.1.2),it is equivalent to H10 (Ω) = {v : v ∈ H1(Ω), v|.Ω = 0}.In addition, let C∞# (Ω) = {v : v ∈ C∞(Ω), v|Γ1 = 0},V (Ω) = closure ofC∞# (Ω) under the norm(1.1.2),which is equivalent toV = {v : v ∈ H1(Ω), v|Γ1 = 0}.
It is clear that V is a Hilbert space with inner product (1.1.3). Furthermore,H10 (Ω) . V . H1(Ω).Let us introduce bilinear functional
(1.1.4) In (1.1.4), fixed u, then B(u, v) is a linear functional of v, while v is fixed, it is a linear functional of u. In other words, suppose α1, α2, β1, β2 are arbitrary constants, then B(α1u1 + α2u2, β1v1 + β2v2) =α1β1B(u1, v1) + α1β2B(u1, v2) + α2β1B(u2, v1) + α2β2B(u2, v2), .u1, u2, v1, v2 ∈ H1(Ω). It is clear that (1.1.4) satisfies
(1) Symmetry,B(u, v) = B(v, u). (1.1.5)
(2) The continuity in V × V , i.e., there exists a constant M >0, such that|B(u, v)| M u 1,Ω v 1,Ω, .u, v ∈ V. (1.1.6)
(3) Coerciveness in V , i.e., there exists constant γ > 0, such that B(u, u) γ u 2 1,Ω, .u ∈ V. (1.1.7) Of course, is a continuous linear functional in v.
The Galerkin Variational Formulation for (1.1.1): Find u ∈ V , such thatB(u, v) = f(v), .v ∈ V. (1.1.8)A solution u satisfying (1.1.8) is called a weak solution of (1.1.1). The space V is calledadmissible space or trial space. On the other hand, (1.1.8) must be satisfied for every v ∈ V ,therefore, V is called test function space. If trial and test space for the variational problem arethe same Hilbert V , in this case, V is called energy space.
Owing to the boundary condition on Γ2 is contained in the variational problem (1.1.8), theboundary condition on Γ2 is called nature boundary condition, while the boundary conditiononΓ1 is called essential boundary condition.
The following proposition gives the relationship between classical solution and weak solution of (1.1.1).
Proposition 1.1 Suppose u ∈ C2(Ω). If u is a classical solution of (1.1.1), then, u isthe weak solution of (1.1.1). Otherwise, if u is a weak solution of (1.1.1), then u is a classicalsolution of (1.1.1).
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前言/序言
好的,根据您的要求,我将为您撰写一本不同于《有限元方法及其应用(英文版) [Finite Element Method and its Applications]》的图书简介。由于您要求内容详细且不包含原书的任何信息,且字数大约1500字,我将围绕一个完全不同的、深入的科学或工程主题进行构思。 --- 图书简介: 书名:高维拓扑结构中的量子场论导论:规范对称性与引力统一的路径探索 作者: 维克多·卡尔森 (Victor Carlson) 出版社: 普林斯顿大学出版社 (Princeton University Press) --- 导言:超越四维时空的基本结构 自二十世纪初以来,人类对物质和能量的理解便建立在量子场论(Quantum Field Theory, QFT)的坚实基石之上。标准模型成功地描述了电磁、弱核和强核三种基本相互作用,而引力,则由爱因斯坦的广义相对论掌管。然而,一个深刻的、悬而未决的问题始终困扰着理论物理学家:如何将量子场论的精确性与描述时空几何的广义相对论进行兼容?尤其是在极高能量尺度或极小距离下,描述宇宙的终极理论必然要求一个超越四维闵可夫斯基时空框架的数学描述。 本书《高维拓扑结构中的量子场论导论:规范对称性与引力统一的路径探索》正视了这一挑战。它并非传统意义上对标准模型或基本弦理论的概述,而是聚焦于构建一个更为基础的数学框架——拓扑场论(Topological Field Theories, TQFTs),并探索如何利用高维、非黎曼几何结构来重构引力理论,使其能够自然地融入量子力学的框架之中。 本书的目标读者是具备扎实高等数学基础(微分几何、代数拓扑)和量子场论背景(路径积分、重整化群)的研究生、博士后研究人员以及专业物理学家。我们旨在提供一个严格的数学推导过程,清晰地勾勒出从经典几何概念过渡到前沿量子引力模型的必要步骤。 第一部分:拓扑场的数学基石 (The Mathematical Foundations of Topological Fields) 本书的开篇部分(第1章至第3章)专注于奠定必要的数学工具。我们摒弃了传统物理教材中对局域能量密度的依赖,转而采用同调理论(Homology Theory)和上同调理论(Cohomology Theory)来描述物理场的性质。 第1章:流形、纤维丛与规范对称性重访 本章首先回顾了微分几何的基础,重点强调了联络(Connections)和曲率(Curvature)在高维流形上的定义。但区别于标准方法,我们引入了层论(Sheaf Theory)的概念,用以描述在奇异点(如奇点或边界)附近局部不变但全局非平凡的场结构。规范对称性不再被视为简单的局域酉变换,而是被提升到对特定纤维丛上的横截面(Sections)保持不变的对称性。我们详细分析了Chern-Simons理论在三维流形上的构造,并展示了其与经典规范理论的深刻联系。 第2章:同调与量子算符 引入拓扑场论的核心概念:物理观测值(如散射矩阵元素)不依赖于流形的度量(Metric),而仅依赖于其拓扑不变量。我们详细推导了Witten的构造,展示如何通过引入特定的拉格朗日密度,使得作用量(Action)仅依赖于流形的拓扑属性。章节重点讨论了奇异同调与奇异上同调如何被用于定义物理态(Hilbert Space)的基础,特别是如何将Bordism群与量子场论的演化算符联系起来,为处理带边界的物理系统奠定基础。 第3章:非交换几何与场论的重构 为了应对引力与量子力学在微观尺度上的不相容性,我们探索了非交换几何(Noncommutative Geometry)在场论中的应用。我们分析了如何用非交换代数取代经典的微分流形,从而在理论层面消除零距离点之间的区分。本章详细介绍了Spectral Triples的概念,并展示了如何利用它们来构建一个对洛伦兹对称性保持不变的“广义”时空结构,这是通向量子引力构造的先驱性工作。 第二部分:引力的拓扑重述与高维嵌入 (Topological Recasting of Gravity and Higher Dimensional Embedding) 本书的第二部分(第4章至第6章)将视角投向引力本身,探讨如何将爱因斯坦的场方程置于一个更广阔的几何框架内。 第4章:重力作为规范场论:Palatini作用量与Twistor理论的交汇 我们重新审视了Palatini作用量,将其视为一个定义在更高阶微分形式上的规范理论。本章详尽地分析了自旋联络和度量张量作为独立变量的处理方式,这使得我们可以更清晰地看到引力与杨-米尔斯理论的结构相似性。随后,我们深入探讨了Penrose的Twistor理论,特别是在零惯性系(Null Coordinates)下的表示。通过构建四维时空上的超对称Twistor理论,我们展示了如何通过对自由度进行精细选择,使得引力场方程自然地从规范对称性中涌现出来。 第5章:Kaluza-Klein理论的现代修正与边界条件 经典Kaluza-Klein理论受困于其对宏观尺度的不切实际预测。本章则聚焦于紧致化(Compactification)的现代处理方式。我们分析了Calabi-Yau流形上的场论,特别是如何利用流形上的霍奇对偶性(Hodge Duality)来确定额外维度中场的稳定性和质量谱。我们详细推导了非紧致维度的动力学行为,并讨论了由Flux(通量)引起的真空能问题,这是理解有效场论的关键。 第6章:膜世界场景与AdS/CFT对偶性:拓扑视角 本章探讨了将场论嵌入高维背景的最新进展。我们以AdS/CFT对偶性(反德西特空间/共形场论对偶)为核心,但着重于其拓扑含义。我们阐述了如何将AdS空间上的引力理论(包含量子修正)映射到其边界上的一个CFT(共形场论),后者本质上是一个受拓扑约束的理论。特别是,我们分析了在AdS/CFT框架下,Entanglement Entropy(纠缠熵)如何通过Ryu-Takayanagi公式与几何(测地线长度)联系起来,从而揭示引力几何本身可能是信息论和拓扑结构涌现的产物。 第三部分:量子引力的非微扰探究 (Non-Perturbative Investigations into Quantum Gravity) 本书的收官部分(第7章和第8章)聚焦于构建完整的、非微扰的量子引力框架。 第7章:循环量子引力与自旋网络 我们对圈量子引力(Loop Quantum Gravity, LQG)的数学形式进行了严格的审查。不同于微扰方法,LQG将时空本身视为由自旋网络(Spin Networks)构成的离散结构。本章详细介绍了Ashtekar变量的重新参数化,以及如何使用Holonomy(路径积分)来定义约束方程。我们推导了圈量子宇宙学(Loop Quantum Cosmology)的基本方程,并讨论了“大反弹”(Big Bounce)的物理意义,这提供了对传统奇点概念的替代方案。 第8章:信息、熵与统一理论的终极展望 最后,本章将信息论、热力学与拓扑结构联系起来,探讨统一理论的哲学和数学前沿。我们讨论了Black Hole Entropy(黑洞熵)的微观起源,并展示了拓扑量子场论如何提供一个无依赖于度量(Metric-independent)的计数方法。我们探讨了全息原理(Holography)的更深层含义——物理定律可能并非植根于时空结构,而是植根于对高维信息集合的特定操作和投影。本书以一个开放性的讨论结束,展望未来理论如何能够利用张量网络(Tensor Networks)等新兴工具,在不依赖传统背景几何的情况下,完全描述量子场与引力动力学。 --- 总结: 本书提供了一条严谨的、从纯数学结构通往统一物理理论的路线图。它避开了对标准弦论的传统描述,而是深入探讨了拓扑、规范对称性以及高维几何在量子引力构造中的核心作用。通过对自旋网络、非交换几何和AdS/CFT对偶性的深入剖析,读者将获得一个全新的视角,理解我们所处的四维时空可能仅仅是更深层、更抽象的拓扑结构在特定边界条件下的投影。本书是物理学前沿研究不可或缺的参考资料。