Modeling and Simulation of Turbulent Mixing and Reaction (eBook)

Preface 6
Acknowledgements 8
Contents 9
Contributors 11
Low-Speed Turbulent Shear-Driven Mixing Layers with Large Thermal and Compositional Density Variations 13
1 Introduction 13
2 Governing Equations 15
2.1 Single-Fluid Case with Temperature Variations 17
2.2 Two-Species Variable-Density Incompressible Case 18
2.3 Discussion 20
3 Simulation Set-Up 21
4 Results 22
5 Conclusions 33
References 34
Scalar Transport Near the Turbulent/Non-Turbulent Interface in Reacting Compressible Mixing Layers 36
1 Introduction 37
1.1 Scalar Transport in Incompressible Free Shear Flows 37
1.2 Motivation and Objective 38
2 Direct Numerical Simulations 39
3 Turbulent/Non-turbulent Interface 43
4 Results and Discussions 45
4.1 Evolution of Scalar-Gradient Magnitude Near the TNTI 46
4.2 Budgets of Scalar-Gradient Magnitude Squared 47
4.3 Heat Release Versus Compressibility Effects 52
5 Summary and Conclusions 55
References 56
Linear Instability of Stably Stratified Down-Slope Flows 58
1 Introduction 58
2 Governing Equations 61
2.1 Prandtl Model for Slope Flows 62
2.2 Dimensionless Numbers 63
3 Linear Modal Analysis 64
3.1 Linear Temporal Growth Rates 65
3.2 Growth Rates for Pure Modes 67
3.3 Eigenfunctions and Spectra 68
3.4 Critical Stability Threshold and Map 70
3.5 Influence of Prandtl Number 72
4 Results from Direct Numerical Simulations 72
4.1 Pure Instability Modes 74
4.2 Mixed Instabilities Mode 75
5 Conclusions 77
References 77
Shock-Turbulence Interaction in Variable Density Flows 80
1 Introduction 81
2 Governing Equations and Solution Procedure 83
2.1 Eulerian Method 83
2.2 Lagrangian Method 84
3 Numerical Accuracy 85
4 Results and Discussions 87
4.1 General Effects of Density on STI 87
4.2 Structure and Topology of the Post-shock Turbulence 90
4.3 Lagrangian Dynamics of VGT 96
References 102
Novel Method for Initiation and Control of Combustion 104
1 Introduction 104
2 Governing Equations and Numerical Methodology 107
3 DNS of Planar Turbulent Jets 109
3.1 Flow-Flame Structure 111
3.2 Effects of Various Flow Parameters 115
4 LES/FMDF of RCM with TJI 124
5 Conclusions 133
References 134
Flamelet Modeling for Supersonic Combustion 138
1 Introduction 138
2 Governing Equations 143
2.1 Mixture Fraction 147
2.2 Flamelet Equations 149
2.3 Progress Variable Equation 150
3 Introduction to Supersonic Combustion 151
4 Flamelets and Supersonic Combustion 153
5 HIFiRE Direct Connect Rig (HDCR) 154
5.1 Numerical Approach 156
5.2 Simulations of the HDCR 157
6 Combustion Mode Analysis for the HDCR 160
6.1 Flame Index 162
6.2 Combustion Mode 164
7 Effect of the Pressure 169
8 Effect of the Wall Heat Transfer 170
9 Effect of the Flamelet Model Boundary Conditions 171
10 Summary and Conclusions 173
References 175
Filtered Density Function Implementation in a Discontinuous Spectral Element Method 180
1 Introduction 180
2 Overview of the Discontinuous Spectral Element Method 181
2.1 Considerations When Coupling Methods 184
3 Coupled FDF Formulation 184
3.1 Solution of the Coupled System 185
3.2 Considerations for Unstructured Grids 185
3.3 Considerations for Compressible Flows 186
4 Demonstration 187
5 Concluding Remarks 188
References 190
Modern Developments in Filtered Density Function 192
1 Introduction 192
2 Physical and Computational Modeling 193
3 Simulations and Practical Applications 195
4 Concluding Remarks 198
References 201
Large Eddy Simulations of Flows with Moving Boundaries 212
1 Introduction 212
2 Numerical Methods 215
2.1 Transformation 216
2.2 Arbitrary Lagrangian Eulerian (ALE) Method 216
2.3 Immersed Boundary Method (IBM) 218
3 Recent Large Eddy Simulations and Insights into Flow Physics 221
3.1 Vortex Rings 221
3.2 Hydrokinetic Turbine 221
3.3 Aquatic Swimming 222
3.4 Bio-Inspired Flow Control 225
4 Future Outlook 227
References 229
A Coupled Eulerian-Lagrangian Framework for the Modeling and Simulation of Turbulent Multiphase Flows 237
1 Introduction 237
2 The Point Mass Particle 239
3 Coupled Eulerian-PMP for Phase Tracking 241
3.1 Case Study: Air Blast Atomization with Heat Transfer 243
4 A Fully Consistent PMP 245
4.1 Eulerian-Lagrangian Communication 247
4.2 Discrete Mass and Momentum Integration 249
5 Multiphase LES with the PMP 251
5.1 PMP Turbulence Modeling with the Langevin Equation 253
5.2 Discrete Mass and Momentum Integration 255
6 Summary 257
References 257
Turbulent Suppression in Swirling Sprays 261
1 Introduction 261
2 Experimental Setup 263
3 Experimental Results and Discussions 265
3.1 Atomization Mechanism of a Pressure-Swirl Nozzle 265
3.2 Effect of Swirl on Turbulence 266
4 Theoretical Analysis 268
5 Comparison of Model with Experiments 272
6 Conclusions 273
References 273