IUTAM Symposium on The Physics of Wall-Bounded Turbulent Flows on Rough Walls (eBook)

IUTAM Symposium on The Physics of Wall-Bounded Turbulent Flows on Rough Walls 1
Preface 7
Contents 9
Direct Numerical Simulation and PIV Measurement of Turbulent Boundary Layer over a Rod-Roughened Wall 13
1 Introduction 13
2 Results 15
3 Conclusions and Outlook 22
References 22
Turbulent Flows over Aligned and Inclined Ribs 24
1 Introduction 24
2 Experimental Set-Up and Measurement Procedure 25
3 Results and Discussion 26
4 Concluding Remarks 29
References 30
An Experimental Study of Turbulent Flow in the Vicinity of Transverse Square Bars 31
1 Introduction 31
2 Experimental Setup 32
3 Results and Discussion 32
3.1 Persistent Spatial Velocity Perturbations 34
3.2 Large-Scale Turbulent Velocity Fluctuations 35
4 Conclusions 36
References 36
Boundary Layer Structure over a Two-Dimensional Rough Wall 37
1 Introduction 37
2 Experimental Conditions 38
3 Results 39
4 Conclusions and Outlook 41
References 42
Turbulence in Pipe Flows with Small Relative Roughness 43
1 Introduction 43
2 Apparatus 44
3 Surface Roughness Characterization 45
4 Friction Factor 46
5 Mean Velocity Profiles 46
6 Streamwise Reynolds Normal Stress 47
7 Two-Point Azimuthal Correlations 48
8 Further Examination of the Surface Roughness Characteristics 49
9 Discussion and Conclusions 51
References 52
LDV Measurement Near a Rough Surface for a Turbulent Boundary Layer 53
1 Introduction 53
2 Experimental Apparatus and Conditions 54
3 Results and Discussions 55
4 Conclusions 58
References 58
POD Analysis of the Near-Wall Region of a Rough Wall Turbulent Boundary Layer 59
1 Introduction 59
2 Experimental Setup 60
3 Results 60
3.1 PIV Results 60
3.2 POD Analysis 61
4 Conclusion 64
References 64
An Experimental Study of a Turbulent Wall Jet on Smooth and Rough Surfaces 65
1 Introduction 65
2 Experimental Apparatus 66
3 Results and Discussion 67
4 Conclusions 70
References 70
Turbulent Flow Over Urban-Type Roughness Using PIV 71
1 Introduction 71
2 Experimental Facility and Setup 72
3 Results and Discussions 72
3.1 Mean Flow and Turbulence 72
3.2 Two-Point Correlation Functions 74
4 Conclusions 76
References 76
A High Reynolds Number Turbulent Boundary Layer with Regular `Braille-Type' Roughness 78
1 Introduction 78
2 Experimental Apparatus 79
3 Results 80
3.1 Mean Velocity and Turbulence Intensity 80
3.2 Energy Spectra 82
3.3 Amplitude Modulation 82
4 Conclusions 84
References 84
On the Outer Layer Controversy for a Turbulent Boundary Layer over a Rough Wall 85
1 Introduction 85
2 On the Outer Layer Controversy 87
3 Toward a Possible Resolution of the Difficulty of Measuring < uv>
4 Concluding Remarks 92
References 93
Turbulent Channel Flow over Model ``Dynamic'' Roughness 95
1 Introduction 95
2 Approach 96
3 Results 98
4 Conclusions 100
References 100
Log-Layer Dynamics in Smooth and Artificially-Rough Turbulent Channels 101
1 Introduction 101
2 Wall-Disturbed DNS, or Artificial Roughness 102
3 Linear Model 104
4 Conclusions 106
References 106
Roughness Scaling Parameters in the Fully-Rough Regime 107
1 Introduction 107
2 Results 108
3 Conclusions and Outlook 111
References 111
Transition in Rough Channels 113
1 Introduction 113
2 Transition from Laminar to Turbulent Flows 115
2.1 Single Elements 115
2.2 Distributed Elements 116
3 A Moody Diagram Based on 2+|w 117
4 Conclusions 118
References 118
Effect of Isotropic Free-stream Turbulence in Favorable Pressure Gradient Turbulent Boundary Layers over a Rough Surface 120
1 Introduction 120
2 Experimental Setup 122
3 Mean Velocity Profiles 123
4 Reynolds Stresses Profiles 123
5 Second-Order Structure Function 124
6 Conclusions and Outlook 125
References 126
Particulate Impact and Erosion in a Turbulent Serpentine Channel 127
1 Serpentine Channel 127
References 131
Rough Wall Skin Friction Measurements Using a High Resolution Surface Balance 132
1 Introduction 132
2 Description of the Balance 133
3 Applications 134
4 Discussion and Conclusions 137
References 137
Modified Hierarchy Structure of Rough-Wall Flows 139
1 Introduction 139
2 Hierarchy Attributes 140
3 Hierarchy Connection to Mean Profile 141
4 MMB Properties of Rough-Wall Flows 142
5 Further Investigation of a Modified Hierarchy 143
6 Conclusions and Outlook 144
References 144
Analysis of Instantaneous Velocity Vector in Geostrophic Turbulent Ekman Layer over a Transitional Rough Surface 146
1 Introduction 146
2 Instantaneous Geostrophic Turbulent Momentum Transfer 147
3 Two Layers Theory (Non-substantive Mesolayer) 147
4 Three Layers Theory (Substantive Mesolayer) 150
References 152
Wall Roughness Effects: A Second Law Analysis (SLA) 154
1 Losses in a Flow Field, Rough Wall Impact 154
2 Channel Flow with Rough Walls 157
2.1 Results for Laminar Flows and Validation 157
2.2 Results for Turbulent Flows and Validation 158
3 Conclusions and Outlook 159
References 159
Coherent Structures in Turbulent Flow over Arrays of Cubical Obstacles 160
1 Introduction 160
2 Numerical Procedure and Geometrical Setup 161
3 Instantaneous Visualizations 162
4 Two-Point Correlations 163
5 Budgets of Reynolds Stresses 164
6 Anisotropy Invariants 166
7 Conclusions 167
References 167
Large Roughness Effects in Channel Flow 169
1 Introduction 169
2 Results 170
3 Discussion and Conclusions 174
References 174
Very-Rough-Wall Channel Flows: A DNS Study 176
1 Introduction 176
2 Numerical Method 177
3 Results 179
4 Conclusions 181
References 181