Computational Fluid Dynamics for Built and Natural Environments

This book introduces readers to the fundamentals of simulating and analyzing built and natural environments using the Computational Fluid Dynamics (CFD) method. CFD offers a powerful tool for dealing with various scientific and engineering problems and is widely used in diverse industries. This book focuses on the most important aspects of applying CFD to the study of urban, buildings, and indoor and outdoor environments. Following the logical procedure used to prepare a CFD simulation, the book covers e.g. the governing equations, boundary conditions, numerical methods, modeling of different fluid flows, and various turbulence models. Furthermore, it demonstrates how CFD can be applied to solve a range of engineering problems, providing detailed hands-on exercises on air and water flow, heat transfer, and pollution dispersion problems that typically arise in the study of buildings and environments. The book also includes practical guidance on analyzing and reporting CFD results, as well as writing CFD reports/papers. Contents 6 1 Introduce CFD 9 1.1 What Is Fluid Mechanics 9 1.2 How to Study Fluid Mechanics 10 1.3 What Is CFD? 15 1.4 How Old Is CFD? 15 1.5 What Is CFD Used for? 16 1.6 How Does CFD Make Predictions? 23 1.7 Can CFD Be Trusted? 25 1.8 How Does One Become a CFD User and a CFD Pro? 26 Practice-1: Outdoor Isothermal Flow 28 Assignment-1: Simulating 2-D Flow Past a 2-D Square Cylinder 31 References 32 2 Model Real Problems 34 2.1 General CFD Modeling Procedure 34 2.2 General Rules for Model Simplification 36 2.3 Classification of Fluids and Flows 37 2.4 Definition of Computational Domain 39 2.5 Abstraction of Physical Objects 45 Practice-2: Forest Canopy Flow 49 Assignment-2: Simulating 3-D Flow Past a Heated 3-D Cube on a Plate 53 References 55 3 Select Equations to Be Solved 57 3.1 Fluid Mechanics Analysis System: Reynolds Transport Theorem 57 3.2 Fluid Mechanics Conservation Equations in Integral Form 58 3.3 Fluid Mechanics Conservation Equations in Differential Form 61 3.4 Transport Equations for Particle and Droplet 70 Practice-3: Indoor Airflow and Heat Transfer 80 Assignment-3: Simulating Wind Flow Pattern across an Urban Environment 86 References 88 4 Select Turbulence Modeling Method 89 4.1 Overview of Turbulence 89 4.2 Direct Numerical Simulation (DNS) 91 4.3 Large Eddy Simulation (LES) 92 4.4 Reynolds-Averaged Navier-Stokes (RANS) Equations 93 4.5 Turbulence Models 94 4.6 Select Proper Turbulence Modeling Method 104 Practice-4: Outdoor Simulation with Different Turbulence Models 106 Assignment-4: Simulating Pollutant Dispersion across an Urban Environment 115 References 117 5 Select Numerical Methods 121 5.1 Discretization Methods (FDM, FVM, FEM) 121 5.2 Discretization of Governing Equations with FDM 128 5.3 Discretization of Governing Equations with FVM 131 5.4 Explicit and Implicit Method 139 Practice-5: Indoor Airflow and Fire in a Long Tunnel 140 Assignment-5: Simulating Natural Convection in a Confined Space 143 References 144 6 Specify Boundary Conditions 146 6.1 Classic Boundary Conditions 146 6.2 Practical Boundary Conditions 150 Practice-6: Simulation of Computer Rack in Data Center 153 Assignment-6: Simulating Forced Convection in a Confined Space 158 References 159 7 Generate Grid 160 7.1 Grid Classification 160 7.2 Advanced Grid Systems 167 7.3 Grid Quality Control 171 7.4 Numerical Viscosity 173 7.5 Applications of Structured Coarse Grids 179 Practice-7: 3-D Indoor Modeling with Optimized Coarse Grids 184 Assignment-7: Simulating Mixed Convection in a Confined Space 186 References 189 8 Solve Case 190 8.1 General Solution Methods 190 8.2 Velocity-Pressure Decoupling Algorithms 196 8.3 Solution Procedure 203 8.4 Convergence and Stabilization 204 Practice-8: Fast CFD Modelling 206 Assignment-8: Simulating Microenvironment Around Thermal Manikin 217 References 219 9 Analyze Results 222 9.1 Result Visualization 222 9.2 Quantitative Comparison 224 9.3 Result Verification and Validation 224 9.4 Simulation Revision 233 9.5 Parametric Study 234 Practice-9: Simulation of Building Integrated Photovoltaic-Thermal Collector 234 Assignment-9: Simulating Displacement Ventilation in a Confined Space 241 References 244 10 Write CFD Report 245 10.1 General Requirements for Reporting CFD Results 245 10.2 Writing CFD Reports for Technical or Course Projects 249 10.3 Writing CFD Articles for Formal Publications 253 Practice-10: Coupled Indoor and Outdoor Simulation with Air-to-Water Heat Exchange Using Multi-Block Meshes 255 Assignment-10: Overall Review Questions 264 References 266 Front Matter ....Pages i-ix Introduce CFD (Zhiqiang (John) Zhai)....Pages 1-25 Model Real Problems (Zhiqiang (John) Zhai)....Pages 27-49 Select Equations to Be Solved (Zhiqiang (John) Zhai)....Pages 51-82 Select Turbulence Modeling Method (Zhiqiang (John) Zhai)....Pages 83-114 Select Numerical Methods (Zhiqiang (John) Zhai)....Pages 115-139 Specify Boundary Conditions (Zhiqiang (John) Zhai)....Pages 141-154 Generate Grid (Zhiqiang (John) Zhai)....Pages 155-184 Solve Case (Zhiqiang (John) Zhai)....Pages 185-216 Analyze Results (Zhiqiang (John) Zhai)....Pages 217-239 Write CFD Report (Zhiqiang (John) Zhai)....Pages 241-263