Flow control : fundamentals and practices

Lecture Notes in Physics: Monographs 53 ......Page 1
Flow Control: Fundamentals and Practices ......Page 3
Copyright ......Page 4
Preface ......Page 5
Contents ......Page 9
Contributors ......Page 11
1 What Is Flow Control ......Page 13
2 Five Eras of Flow Control ......Page 14
3 Governing Equations ......Page 16
3.1 Equations of Motion at the Wall ......Page 19
3.2 The Kármán Integral Equation ......Page 20
3.3 Turbulent Flows ......Page 21
4.1 Control Goals and Their Interrelation ......Page 22
4.2 Classification Schemes ......Page 23
4.3 Free-Shear and Wall-Bounded Flows ......Page 27
4.4 Regimes of Reynolds and Mach Numbers ......Page 28
4.5 Convective and Absolute Instabilities ......Page 29
5 Transition Delay ......Page 30
5.1 Stability Modifiers ......Page 32
5.2 Wave Cancellation ......Page 39
5.3 Compliant Coatings ......Page 40
6.1 Steady Separation ......Page 41
6.2 Unsteady Separation ......Page 42
6.3 Velocity Profile Modifiers ......Page 45
6.4 Moving Walls ......Page 51
6.5 Time-Dependent Separation ......Page 53
6.7 Turbulators ......Page 55
6.8 Momentum Addition to Near-Wall Flow ......Page 58
6.9 Separation Provocation ......Page 67
7.1 Introductory Remarks ......Page 68
7.2 Turbulent Flows ......Page 71
7.3 Relaminarization ......Page 81
7.4 Synergism ......Page 83
8 Turbulence Augmentation ......Page 86
9 Noise Control ......Page 87
10 Concluding Remarks ......Page 90
References ......Page 92
1.1 The Taming of the Shrew ......Page 121
1.2 Control of Turbulence ......Page 122
2 Suction ......Page 123
3 Coherent Structures ......Page 125
4.1 Introductory Remarks ......Page 129
4.2 Targeted Control ......Page 130
4.3 Reactive Feedback Control ......Page 134
4.4 Required Characteristics ......Page 136
5.1 Nonlinear Dynamical Systems Theory ......Page 138
5.2 Chaos Control ......Page 141
6 Microfabrication ......Page 145
7 Soft Computing ......Page 148
7.1 Neural Networks ......Page 152
8 Concluding Remarks ......Page 155
References ......Page 156
1 The Structure of the Bursting Process ......Page 167
1.1 Length and Velocity Scales ......Page 169
1.2 The Principal Eddies in the Bursting Process ......Page 171
1.3 Inner-Outer Relationship in the Shear Flow ......Page 179
2 Analogies with Transitional Flows ......Page 180
3 Aspects of Control of Bounded Turbulent Flows ......Page 189
3.1 Global versus Selective Control ......Page 193
3.2 Selective Suction ......Page 194
3.3 Spanwise Wall Disturbances ......Page 196
3.4 Actuators in the Wall Region ......Page 199
3.5 Control Algorithms ......Page 203
Acknowledgments ......Page 205
References ......Page 206
1 Introduction ......Page 211
1.1 Tools and Methods ......Page 213
1.2 Active Control ......Page 214
2.1 Overview ......Page 217
2.2 Accessing the Large-Scale Structure ......Page 219
2.3 Excited vs Natural Approaches ......Page 221
2.4 Detection Methods ......Page 222
3.1 The POD Approach in Brief ......Page 227
3.2 Formal Definition of POD ......Page 228
3.3 The POD Theorem ......Page 229
3.4 Different POD Approaches ......Page 231
3.6 Evaluative Summary of the POD Approach ......Page 234
3.7 Some Typical Applications of POD ......Page 236
3.8 Some Typical Results: Application to the Plane Mixing Layer. ......Page 238
3.9 LSE and Complementary Technique. ......Page 246
4.1 Deterministic Approach of Turbulence ......Page 252
4.2 Development of POD Based Dynamical System ......Page 253
4.4 Vorticity Transport Equation ......Page 259
4.5 The Plane Mixing Layer ......Page 260
4.6 Representativity of the Dynamical System Model ......Page 266
5 Concluding Remarks ......Page 273
References ......Page 276
Books/Workshops ......Page 284
1.1 Physics of Multiscale Flows ......Page 287
1.2 Modeling of Unsteady Flows ......Page 295
1.3 Theoretical Problems Related to Control ......Page 300
2.1 Enhancement of Perturbation Process ......Page 306
2.2 Strategies of Control ......Page 307
2.3 Cost Function and Heat and Mass Transfer Enhancement ......Page 309
2.4 Basic Flow Characteristics and their Use in Control ......Page 311
2.5 Critical Point Design and Control ......Page 314
2.7 Experimental Work in Progress ......Page 316
3.1 Strategies of Control ......Page 317
3.2 Applicability of the Strategies ......Page 321
3.3 Control of Flows with Internal Mode Coupling ......Page 323
3.4 Direct Control of Separation ......Page 329
4.1 Introduction to Engineering Problems ......Page 330
4.2 Problems of Methodology ......Page 331
4.3 Basic Problems for Design ......Page 332
4.4 Design for Qualification, Certification ......Page 334
5 Parting Remark ......Page 335
References ......Page 336
1.2 Description-Typology and Characterization of Free Shear Flows ......Page 347
1.3 Control Versus Management ......Page 348
1.4 Some History ......Page 349
1.5 What Do We Want to Achieve? – Aims of Control ......Page 351
1.6 What Mean Do We Command? – Methods and Mechanisms ......Page 352
1.9 Summary and Charts ......Page 365
2.1 Introduction – Definitions, Configurations, Concepts ......Page 367
2.2 Jets ......Page 370
2.3 Wakes ......Page 384
2.4 Juxtaposition and Summary ......Page 390
3.1 Introduction, Configurations, Definitions ......Page 392
3.2 Purpose of Control – Goals ......Page 393
3.3 Stability and Structures ......Page 394
3.4 Control via Boundary Conditions ......Page 397
3.5 Control via Flow Field / Field Effects ......Page 409
3.6 Three-Dimensional Configurations and Special Effects ......Page 412
4.2 Separating/Separated Flows (Mixing Layer with Wall Effects) ......Page 421
4.3 Confined Flow ......Page 427
4.4 Combined Flows ......Page 428
5 General Surnmary ......Page 430
References ......Page 432
2 Riblets ......Page 443
2.2 Spectral-Element-Fourier Methods ......Page 446
2.3 Finite Volume Methods ......Page 448
2.4 Viscous Wall Region Modelling ......Page 449
2.5 Results from Near-Wall Viscous Model and Direct Numerical Simulations ......Page 453
3 Alternative and Complementary Techniques ......Page 459
3.1 Three Dimensional Riblets or Humplets ......Page 460
3.2 Wall Oscillation ......Page 462
3.3 Selective Interference ......Page 465
3.4 Selective Introduction Tecliniques ......Page 469
4 Concluding Remarks ......Page 470
References ......Page 471
1 Introduction ......Page 479
2 System review ......Page 480
2.1 Background material on coupling mechanisms ......Page 481
2.3 Active combustion control ......Page 484
2.4 System identification ......Page 486
2.5 Active fluid mechanics and active combustion control ......Page 487
3.1 Actuators ......Page 490
3.2 Closed-loop control ......Page 491
3.3 Open-loop control ......Page 492
4.1 Interactions between laminar flames and upstream flow modulations ......Page 495
4.2 Forcing of a turbulent ducted flame by longitudinal acoustic modes ......Page 497
4.3 Modulation of a turbulent spray flame ......Page 498
5 Application to pollutant emission ......Page 502
5.1 NO_x reduction: global effects ......Page 503
5.2 NO_x reduction: local effects ......Page 504
6 Conclusions ......Page 505
References ......Page 506
1 Historical Setting ......Page 513
2 Control of Temporal Chaos ......Page 514
2.1 Using Chaotic Sensitivity ......Page 516
2.2 Implementations ......Page 517
2.3 Higher Dimensionality ......Page 521
3 Control of Spatial Chaos ......Page 523
3.1 Horseshoes in Mbdng Flows ......Page 526
3.2 Implementations ......Page 529
3.3 Coherent Structure Creation in Standard Map ......Page 531
3.4 Coherent Structure Creation in Chaotic Fluid Flow ......Page 533
4 Prognostication ......Page 536
References ......Page 537