内容简介
     We were pleasantly surprised by the ready acceptance of the first edition of our book by the CFD community and by the amount of positive feedback received over a period of 10 years. To us this has provided justification of our original plan, which was to provide an accessible introduction to this fast-growing topic to support teaching at senior undergraduate level, post- graduate research and new industrial users of commercial CFD codes. Our second edition seeks to enhance and update. The structure and didactic approach of the first edition have been retained without change, but aug- mented by a selection of the most important developments in CFD.     
内页插图
          目录
   Preface
Acknowledgements
1 Introduction
1.1 What is CFD?
1.2 How does a CFD code work?
1.3 Problem solving with CFD
1.4 Scope of this book
2 Conservation laws of fluid motion and boundary conditions
2.1 Governing equations of fluid flow and heat transfer
2.2 Equations of state
2.3 Navier-Stokes equations for a Newtonian fluid
2.4 Conservative form of the governing equations of fluid flow
2.5 Differential and integral forms of the general transport equations
2.6 Classification of physical behaviours
2.7 The role of characteristics in hyperbolic equations
2.8 Classification method for simple PDEs
2.9 Classification of fluid flow equations
2.10 Auxiliary conditions for viscous fluid flow equations
2.11 Problems in transonic and supersonic compressible flows
2.12 Summary
3 Turbulence and its modelling
3.1 What is turbulence?
3.2 Transition from laminar to turbulent }low
3.3 Descriptors of turbulent flow
3.4 Characteristics of simple turbulent flows
3.5 The effect of turbulent fluctuations on properties of the mean flow
3.6 Turbulent flow calculations
3.7 Reynolds-averaged Navier-Stokes equations and classical turbulence models
3.8 Large eddy simulation
3.9 Direct numerical simulation
3.10 Summary
4 The finite volume method for diffusion problems
4.1 Introduction
4.2 Finite volume method for one-dimensional steady state diffusion
4.3 Worked examples: one-dimensional steady state diffusion
4.4 Finite volume method for two-dimensional diffusion problems
4.5 Finite volume method for three-dimensional diffusion problems
4.6 Summary
5 The finite volume method for convection-diffusion problems
5.1 Introduction
5.2 Steady one-dimensional convection and diffusion
5.3 The central differencing scheme
5.4 Properties of discretisation schemes
5.5 Assessment of the central differencing scheme for convectiondiffusion problems
5.6 The upwind differencing scheme
5.7 The hybrid differencing scheme
5.8 The power-law scheme
5.9 Higher-order differencing schemes for convection-diffusion problems
5.10 TVD schemes
5.11 Summary
6 Solution algorithms for pressure-velocity
6.1 Introduction
6.2 The staggered grid
6.3 The momentum equations
6.4 The SIMPLE algorithm
6.5 Assembly ora complete method
6.6 The SIMPLER algorithm
6.7 The SIMPLEC algorithm
6.8 The PISO algorithm
6.9 General comments on SIMPLE, SIMPLER, SIMPLEC and PISO
6.10 Worked examples of the SIMPLE algorithm
6.11 Summary
7 Solution of discretised equations
7.1 Introduction
7.2 The TDMA
7.3 Application of the TDMA to two-dimensional problems
7.4 Application of the TDMA to three-dimensional problems
7.5 Examples
7.6 Point4terative methods
7.7 Multigrid techniques
7.8 Summary
8 the finite volume method for unsteady flows
8.1 Introduction
8.2 One-dimensional unsteady heat conduction
8.3 Illustrative examples
8.4 Implicit method for two- and three-dimensional problems
8.5 Discretisation of transient convection-diffusion equation
8.6 Worked example of transient convection-diffusion using QUICK differencing
8.7 Solution procedures for unsteady flow calculations
8.8 Steady state calculations using the pseudo-transient approach
8.9 A brief note on other transient schemes
8.10 Summary
9 Implementation of boomfary confftions
9.1 Introduction
9.2 Inlet boundary conditions
9.3 Outlet boundary conditions
9.4 Wall boundary conditions
9.5 The constant pressure boundary condition
9.6 Symmetry boundary condition
9.7 Periodic or cyclic boundary condition
9.8 Potential pitfalls and final remarks
10 Errors and uncertainty in CFD modelling
10.1 Errors and uncertainty in CFD
10.2 Numerical errors
10.3 Input uncertainty
10.4 Physical model uncertainty
10.5 Verification and validation
10,6 Guidelines for best practice in CFD
10.7 Reporting/documentation of CFD simulation inputs and results
10.8 Summary
11 Methods for dealing with complex geometries
11.1 Introduction
11.2 Body-fitted co.ordinate grids for complex geometries
11.3 Catesian vs. curvilinear grids - an example
11.4 Curvilinear grids - difficulties
11.5 Block-structured grids
11.6 Unstructured grids
11.7 Discretisation in unstructured grids
11.8 Discretisafion of the diffusion term
11.9 Discretisafion of the convective term
11.10 Treatment of source terms
11.11 Assembly of discretised equations
11.12 Example calculations with unstructured grids
11.13 Pressure-velocity coupling in unstructured meshes
11.14 Staggered vs. co-located grid arrangements
11.15 Extension of the face velocity interpolation method to unstructured meshes
11.16 Summary
12 CFD modelling of combustion
12.1 Introduction
12.2 Application of the first law of thermodynamics to a combustion system
12.3 Enthalpy of formation
12.4 Some important relationships and properties of gaseous mixtures
12.5 Stoichiometry
12.6 Equivalence ratio
12.7 Adiabatic flame temperature
12.8 Equilibrium and dissociation
12.9 Mechanisms of combustion and chemical kinetics
12.10 Overall reactions and intermediate reactions
12.11 Reaction rate
12.12 Detailed mechanisms
12.13 Reduced mechanisms
12.14 Governing equations for combusting flows
12.15 The simple chemical reacting system (SCRS)
12.16 Modelling of a laminar diffusion flame - an example
12.17 CFD calculation of turbulent non-premixed combustion
12.18 SCRS model for turbulent combustion
12.19 Probability density function approach
12.20 Beta pdf
12.21 The chemical equilibrium model
12.22 Eddy break-up model of combustion
12.23 Eddy dissipation concept
12.24 Laminar flamelet model
12.25 Generation oflaminar, flamelet libraries
12.26 Statistics of the non-equilibrium parameter
12.27 Pollutant formation in combustion
12.28 Modelling of thermal NO formation in combustion
12.29 Flamelet-based NO modelling
12.30 An example to illustrate laminar flamelet modelling and NO modelling of a turbulent flame
12.31 Other models for non-premixed combustion
12.32 Modelling ofpremixed combustion
12.33 Summary
13 Numedcal calculation of radiative heat transfer
13.1 Introduction
13.2 Governing equations of radiative heat transfer
13.3 Solution methods
13.4 Four popular radiation calculation techniques suitable for CFD
13.5 Illustrative examples
13.6 Calculation of radiative properties in gaseous mixtures
13.7 Summary
Appendix A Accuracy of a flow simulation
Appendix B Non-uniform grids
Appendix C Calculation of source terms
Appendix D Limiter functions used in Chapter 5
Appendix E Derivation of one-dimensional governing equations for steady, incompressible flow through a planar nozzle
Appendix F Alternative derivation for the term (n . grad Ai) in Chapter 11
Appendix G Some examples
Bibliography
Index      
精彩书摘
     The discussion of the k-e turbulence model, to which we return later, the material in Chapters 2 and 3 is largely self-contained. This allows the use of this book by those wishing tO concentrate principally on the numerical algorithms, but requiring an overview of the fluid dynamics and the math- ematics behind it for occasional reference in the same text.
  The second part of the book is devoted to the numerical algorithms of the finite volume method and covers Chapters 4 to 9. Discretisation schemes and solution procedures for steady flows are discussed in Chapters 4 to 7. Chapter 4 describes the basic approach and derives the central difference scheme for diffusion phenomena. In Chapter 5 we emphasise the key prop- erties of discretisation schemes, conservativeness, boundedness and trans- portiveness, which are used as a basis for the further development of the upwind, hybrid, QUICK and TVD schemes for the discretisation of con- vective.terms. The non-linear nature of the underlying flow phenomena and the linkage between pressure and velocity in variable density fluid flows requires special treatment, which is the subject of Chapter 6. We introduce the SIMPLE algorithm and some of its more recent derivatives and also discuss the PISO algorithm. In Chapter 7 we describe algorithms for the solution of the systems of algebraic equations that appear after the discret- isation stage. We focus our attention on the well-known TDMA algorithm, which was the basis of early CFD codes, and point iterative methods with multigrid accelerators, which are the current solvers of choice.The theory behind all the numerical methods is developed around a set of worked examples which can be easily programmed on a PC. This pres- entation gives the opportunity for a detailed examination of all aspects of the discretisation schemes, which form the basic building blocks of practical CFD codes, including the characteristics of their solutions.
  In Chapter 8 we assess the advantages and limitations of various schemes to deal with unsteady flows, and Chapter 9 completes the development of the numerical algorithms by considering the practical implementation of the most common boundary conditions in the finite volume method.
  The book is primarily aimed to support those who have access to a CFD package, so that the issues raised in the text can be explored in greater depth. The solution procedures are nevertheless sufficiently well documented for the interested reader to be able to start developing a CFD code from scratch.
  The third part of the book consists of a selection of topics relating to the application of the finite volume method to complex industrial problems. In Chapter 10 we review aspects of accuracy and uncertainty in CFD. It is not possible to predict the error in a CFD result from first principles, which creates some problems for the industrial user who wishes to evolve equip- ment design on the basis of insights gleaned from CFD. In order to address this issue a systematic process has been developed to assist in the quantifica- tion of the uncertainty of CFD output. We discuss methods, the concepts of verification and validation, and give a summary of rules for best practice that have been developed by the CFD community to assist users. In Chapter 11 we discuss techniques to cope with complex geometry. We review various approaches based on structured meshes: Cartesian co-ordinate systems, gen- eralised co-ordinate systems based on transformations, and block-structured grids, which enable design of specific meshes tailored to the needs of dif- ferent parts of geometry. We give details of the implementation of the finite volume method on unstructured meshes. These are not based on a grid of lines to define nodal.      
前言/序言
     We were pleasantly surprised by the ready acceptance of the first edition of our book by the CFD community and by the amount of positive feedback received over a period of 10 years. To us this has provided justification of our original plan, which was to provide an accessible introduction to this fast-growing topic to support teaching at senior undergraduate level, post- graduate research and new industrial users of commercial CFD codes. Our second edition seeks to enhance and update. The structure and didactic approach of the first edition have been retained without change, but aug- mented by a selection of the most important developments in CFD.
  In our treatment of the physics of fluid flows we have added a summary of the basic ideas underpinning large-eddy simulation (LES) and direct numerical simulation (DNS). These resource-intensive turbulence predic- tion techniques are likely to have a major impact in the medium term on CFD due to the increased availability of high-end computing capability.
  Over the last decade a number of new discretisation techniques and solution approaches have come to the fore in commercial CFD codes. To reflect these developments we have included summaries of TVD techniques, which give stable, higher-order accurate solutions of convection-diffusion problems, and of iterative techniques and multi-grid accelerators that are now commonly used for the solution of systems of discretised equations. We have also added examples of the SIMPLE algorithm for pressure-velocity coupling to illustrate its workings.
  At the rime of writing our first edition, CFD was firmly established in the aerospace, automotive and power generation sectors. Subsequently, it has spread throughout engineering industry. This has gone hand in hand with major improvements in the treatment of complex geometries. We have devoted a new chapter to describing key aspects of unstructured meshing techniques that have made this possible.
  Application of CFD results in industrial research and design crucially hinges on confidence in its outcomes. We have included a new chapter on uncertainty in CFD results. Given the rapid growth in CFD applications it is difficult to cover, within the space of a single introductory volume, even a small part of the submodelling methodology that is now included in many general-purpose CFD codes. Our selection of advanced application material covers combustion and radiation algorithms, which reflects our local perspec- tive as mechanical engineers with interest in internal flow and combustion.    
				
 
				
				
					流体运动的计算之旅:一窥数值模拟的广阔天地  本书旨在为读者提供一个坚实的基础,帮助他们理解和掌握现代流体力学研究与工程应用中至关重要的一环——计算流体力学 (CFD) 的核心原理与实践方法。我们将聚焦于如何将复杂的流体物理现象,通过严谨的数学建模和高效的数值求解技术,转化为计算机可以处理和分析的离散方程,从而揭示流体在各种工况下的行为模式。  我们深知,流体力学的领域博大精深,涵盖了从宏观的气象预报到微观的生物医学流动。因此,本书的叙事结构被精心设计,力求在保持学术深度的同时,确保初学者也能平稳过渡,而有经验的工程师也能从中汲取新的见解。本书的重点不在于对特定商业软件的使用手册进行详述,而是着眼于方法论的构建与理解,这是构建任何成功流体模拟系统的基石。   第一部分:理论基石与物理背景  在正式进入数值方法之前,我们必须对流体运动背后的基本物理定律有一个清晰的认识。本部分将回顾和阐述支配所有流体现象的基本控制方程组——纳维-斯托克斯(Navier-Stokes, N-S)方程。我们将深入探讨这些方程的物理意义,分析其非线性和耦合特性,并讨论在不同流动背景下(如不可压缩、可压缩、粘性、无粘性)方程的简化形式及其适用范围。理解这些微分方程的精髓,是后续将其转化为可求解代数形式的前提。  我们还将详细考察流体动力学的分类。从层流到湍流的过渡,是CFD领域最具挑战性的课题之一。本书将对湍流的统计特性、雷诺平均纳维-斯托克斯(RANS)方程的引入进行必要的铺垫,并简要介绍大涡模拟(LES)和直接数值模拟(DNS)的基本思想,为读者勾勒出应对不同复杂度的工具箱。此外,边界条件的选择和处理,作为连接物理世界与数学模型的桥梁,其重要性不容忽视,我们将探讨各种常见的入口、出口、壁面及自由边界条件的物理设定与数学表达。   第二部分:数值离散化的核心艺术  流体控制方程本质上是偏微分方程(PDEs),直接求解它们在解析上往往是困难的,在工程实践中更是几乎不可能。因此,我们需要将空间和时间上的连续场域进行“数字化”处理,这就是数值离散化的艺术。  本部分是本书的核心内容之一。我们将系统地介绍几种主要的离散化策略。首先,我们会从泰勒级数展开出发,直观地理解如何用离散点上的值来近似函数在某点的值,这是所有数值方法的出发点。随后,我们将把注意力转向对 PDE 求解至关重要的方法:  1. 有限差分法(Finite Difference Method, FDM)的系统阐述: 虽然本书的侧重点不在于此,但FDM是理解数值扩散、网格依赖性以及离散误差的绝佳起点。我们将讲解如何使用中心差分、迎风差分等不同格式来离散导数项,并讨论这些选择对解的稳定性和精度的深刻影响。  2. 有限体积法(Finite Volume Method, FVM)的深入剖析: 针对实际工程应用中对守恒性(如质量、动量、能量的守恒)的严格要求,FVM因其固有的守恒特性,成为了工业界的主流选择。我们将详细阐述控制方程如何在任意形状的控制体积上通过积分形式被推导出来。重点将放在通量计算上,即如何准确地评估穿过控制体积界面(网格界面)上的物理量输运——这通常是决定解的准确性的关键步骤。  3. 网格生成与质量评估: 数值模拟的“场地”——计算网格——的质量直接决定了模拟的有效性。本部分将探讨结构化网格、非结构化网格的生成技术,以及如何评估网格的质量指标(如正交性、光滑度),并讨论网格无关性(Grid Independence)的验证过程,确保我们的计算结果不是网格的产物,而是物理现象的真实反映。   第三部分:代数系统的求解与耦合机制  完成离散化后,连续的 PDE 系统就被转化为一个巨大的、通常是稀疏的非线性代数方程组。如何有效地求解这些方程组,是决定计算效率和稳定性的关键。  1. 线性系统的求解器: 我们将分类讨论求解线性代数方程组的方法。对于大型稀疏矩阵,迭代求解器(如雅可比法、高斯-赛德尔法,以及更高效的Krylov子空间方法,如GMRES或BiCGSTAB)的原理和收敛性分析是必不可少的。我们还会涉及预处理技术如何加速这些迭代过程。  2. 压力-速度耦合算法: 在不可压缩流(或低速可压缩流)中,N-S方程中压力项与速度项的耦合是一个主要的难点。本部分将详细介绍解决这一问题的经典策略,特别是SIMPLE(Semi-Implicit Method for Pressure Linked Equations)族算法及其后续发展,解释这些算法如何通过压力修正方程,在速度和压力场之间建立反馈机制,确保解的一致性。  3. 稳态与瞬态问题的处理: 求解策略会根据问题的性质有所不同。对于稳态问题,我们将讨论如何利用松弛因子和亚迭代来稳定收敛过程。对于瞬态问题,我们将比较不同时间推进格式(如显式、隐式、半隐式)的稳定性和精度特性,并探讨如何选择合适的时间步长以平衡计算成本和时间分辨率。   第四部分:验证、确认与高级主题概述  一个成功的模拟不仅需要顺利运行,更需要证明其结果是可靠和有意义的。本部分将转向计算结果的评估与应用。  1. 验证(Verification)与确认(Validation): 我们将区分这两个至关重要的概念。验证关注“我们是否正确地求解了方程?”(通常通过网格收敛性、时间步长收敛性测试和与解析解的对比来实现)。确认则关注“我们是否求解了正确的方程?”(即模型是否准确描述了真实的物理现象,需要与实验或现场数据进行对比)。  2. 湍流模型的实际应用: 鉴于湍流的复杂性,我们不会回避对实际工程中常用RANS湍流模型(如 $k-epsilon$ 模型、 $k-omega$ 模型及其剪应力输运模型)的局限性与适用范围的讨论。理解这些模型的物理假设和数值实现上的困难,是避免得出误导性结果的关键。  3. 高级议题的引介: 篇幅所限,我们无法对所有前沿技术进行详尽展开,但会提供必要的概念介绍,包括动网格技术在模拟运动部件中的应用、多相流模型的挑战,以及伴随方法在优化设计中的潜力,引导读者在掌握基础后,继续探索更广阔的CFD前沿领域。  通过对这些理论、方法和实践环节的系统梳理,本书致力于培养读者对计算流体动力学从物理概念到数值实现的全景式理解能力,使读者能够自信地构建、运行和解释复杂的流体模拟项目。