Using Computational Fluid Dynamics

C.T. Shaw

Sujets

• CFD
• Calcul (mathématiques)
• Fluide

Informations

• Publié par: mtoledan
• Publié le: 24 juin 2011
• Nombre de lectures: 101
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

C.T. Shaw, Using Computational Fluid Dynamics, Prentice Hall, 1992 CONTENTS PREFACE.............................................................................7 1 INTRODUCTION .............................................................1 1.1 Using Computers To Predict Flows .............................1 1.2 Situations Where Fluids Flow......................................2 1.3 Why Read This Book ?................................................5 1.4 The Objectives Of The Study ......................................6 1.5 Using The Book ..........................................................7 2 FLUIDS IN MOTION...................................................... 10 2.1 Some Common Flow Features................................... 10 2.1.1 Fluids All Around Us.......................................... 11 2.1.2 The Ways Fluids Flow........................................ 15 2.1.3 Some Properties of Fluids ................................... 16 2.2 Equations Describing Fluids in Motion...................... 18 2.2.1 Developing the Governing Equations.................. 19 2.2.2 Concepts of Turbulence ...................................... 25 2.2.3 Modelling Turbulence......................................... 26 2.3 Obtaining Greater Understanding of Fluid Flow ........ 30 3 NUMERICAL SOLUTIONS TO PARTIAL DIFFERENTIAL EQUATIONS ......................................... 33 3.1 Techniques of Numerical Discretisation .................... 34 3.1.1 The Finite Difference Method............................. 34 3.1.2 The Finite Element Method ................................ 38 3.1.3 The Finite Volume Method................................. 44 3.2 Numerical Discretisation of a Simple Equation.......... 44 3.2.1 Using Finite Differences ..................................... 45 3.2.2 Using Finite Elements......................................... 52 3.2.3 Using Finite Volumes ......................................... 57 3.3 Comparison of the Discretisation Techniques ............ 59 3.4 Producing A Solution From The Discrete Equations.. 62 3.4.1 Convergence and Stability .................................. 63 3.4.2 Solving The Simultaneous Equations.................. 64 3.5 Solving The Coupled Set of Fluid Flow Equations..... 70 C.T. Shaw, Using Computational Fluid Dynamics, Prentice Hall, 1992 3.5.1 Non-Linearity and Time Dependence ................. 70 3.5.2 Obtaining the Pressure Solution.......................... 74 3.5.3 The Convection Operator.................................... 78 3.5.4 Boundary Conditions For Fluid Flow Problems .. 80 4 COMPUTER-BASED ANALYSIS PROCEDURES AND TOOLS............................................................................... 85 4.1 The Analysis Process................................................. 86 4.2 Computer Hardware For CFD.................................... 90 4.2.1 Computers .......................................................... 90 4.2.2 Peripherals.......................................................... 93 4.3 Using the Hardware................................................... 94 4.4 Commercial Software Packages Used For CFD ......... 96 4.4.1 Pre-Processing Programs .................................... 96 4.4.2 Solving The Equations........................................ 97 4.4.3 Post-Processing Programs................................... 98 4.4.4 Utilities............................................................... 98 5 DESCRIBING FLOW PROBLEMS IN ENGINEERING ......................................................................................... 100 5.1 Producing a Specification ........................................ 101 5.1.1 Knowing What Is Required of the Analysis ...... 101 5.1.2 Specifying the Geometry of the Problem........... 103 5.1.3 Defining the Flow............................................. 104 5.2 An Example of a Flow Specification ....................... 106 6 BUILDING A MESH..................................................... 112 6.1 The Need For A Mesh ............................................. 112 6.2 Creating A Mesh For A Given Flow ........................ 113 6.3 Mesh Structures....................................................... 115 6.3.1 The Basic Parts of a Mesh................................. 115 6.3.2 Types of Structure ............................................ 117 6.4 Building Meshes...................................................... 121 6.4.1 Defining the Geometry ..................................... 121 6.4.2 Determining The Mesh Structure...................... 125 6.4.3 Building a Simple Mesh With a Regular Structure .................................................................................. 126 6.4.4 Using Commercial Mesh Generation Software.. 129 6.4.5 Some Automatic Mesh Generation Algorithms . 132 6.5 Modifying An Existing Mesh To Give A Better Solution......................................................................... 137 7 SETTING THE FLUID FLOW PARAMETERS............ 140 7.1 Specifying Fluid Properties ..................................... 141 7.2 Determining the Variables That Need To Be Calculated ...................................................................................... 143 7.3 Finding the Boundaries............................................ 145 7.3.1 Boundaries for Meshes With A Regular Structure .................................................................................. 145 7.3.2 Boundaries for Meshes With An Irregular Structure .................................................................................. 147 7.3.3 Grouping Faces Together.................................. 151 7.4 Defining the Boundary Conditions .......................... 152 7.5 Defining the Initial Conditions ................................ 154 7.6 Using User-Generated Subroutines To Influence The Simulation..................................................................... 155 8 OBTAINING A SOLUTION ......................................... 157 8.1 Final Data Preparation............................................. 157 8.1.1 A Note On Iterative Processes .......................... 157 8.1.2 Controlling The Iterative Processes................... 160 8.1.3 Other Solution Control Information .................. 163 8.2 Running the Solver and Troubleshooting ................. 165 9 ANALYSING THE RESULTS...................................... 170 9.1 The Results Obtained From The Solver ................... 170 9.2 Using Computer Graphics For CFD......................... 173 9.2.1 Using Graphics Hardware................................. 173 9.2.2 Using Graphics Software .................................. 174 9.2.3 Plotting the Geometry....................................... 175 9.2.4 Obtaining the Required View............................ 177 9.2.5 Displaying the Results ...................................... 181 9.2.6 Special Displays ............................................... 184 9.3 Checking A Solution ............................................... 185 C.T. Shaw, Using Computational Fluid Dynamics, Prentice Hall, 1992 9.4 Refining A Computer Model ................................... 186 10 SOME CASE STUDIES .............................................. 188 10.1 The Examples........................................................ 188 10.2 The Software Packages.......................................... 189 10.3 Laminar Flow Between Parallel Plates................... 191 10.3.1 Producing The Flow Specification .................. 191 10.3.2 Some Analysis ................................................ 193 10.3.3 Building a Mesh ............................................. 196 10.3.4 Setting the Fluid Flow Parameters................... 200 10.3.5 Running The Solution..................................... 203 10.3.6 Analysing the Results ..................................... 205 10.4 Turbulent Flow Over a Car .................................... 210 10.4.1 Producing A Flow Specification ..................... 210 10.4.2 Creating A Mesh............................................. 211 10.4.3 Preparing the Data Before Solution................. 215 10.4.4 Running the Solver and Analysing the Results 226 10.4.5 A Note On Three-Dimensional Calculations ... 233 10.5 Water Flow Around A Combustion Chamber ........ 235 10.5.1 Producing A Specification .............................. 235 10.5.2 Producing A Mesh .......................................... 237 10.5.3 Other Pre-Processing Tasks ............................ 240 10.5.4 Running The Solution..................................... 244 10.6 A Review Of The Usefulness Of CFD ................... 248 11 MODELLING FLOWS WITH ADDITIONAL COMPLEXITY................................................................. 250 11.1 Modelling Flows With Heat Transfer..................... 251 11.1.1 The Effects of Heat Transfer on a Flow........... 251 11.1.2 The Energy Equation For Heat Transfer.......... 252 11.1.3 The Effects of Turbulence on Heat Transfer.... 255 11.1.4 Buoyancy Effects............................................ 255 11.1.5 Conjugate Heat Transfer Problems.................. 257 11.1.6 Some Non-Dimensional Groups...................... 259 11.2 Modelling Flows That Are Compressible............... 260 11.2.1 Some Features Found In Compressible Flows. 260 11.2.2 Equations For Compressible Flow .................. 261 11.2.3 Some Practical Problems With Compressible Flows ........................................................................ 263 11.3 Multiple-Phase Flows ............................................ 264 11.4 Modelling the Effects of Combustion .................... 265 12 ACQUIRING CFD TECHNOLOGY ........................... 266 12.1 Preliminaries ......................................................... 266 12.2 Assessing the Need................................................