Laser-strophometry: high-resolution techniques for velocity gradient measurements in fluid flows

Lecture Notes in Physics: Monographs 69......Page 1
Laser-Strophometry......Page 3
Preface......Page 5
Symbols......Page 6
Table of Contents......Page 9
1. Introduction......Page 13
2.1 The Importance of Velocity Gradient Measurement techniques......Page 16
2.2 The Hot Wire Method......Page 20
2.3.1 General Considerations......Page 22
2.3.2 Direct Imaging......Page 24
2.3.3 LDA Laser Doppler Anemometry......Page 26
2.3.4 Laser Doppler Optical Beat......Page 28
2.3.5 The Laser Strophometry......Page 29
2.4 Further Special Methods......Page 30
3.1 Stochastic Quantities......Page 33
3.2. Average Values......Page 34
3.3.1 The probability Dencity......Page 38
3.3.2 Joint Probabilities......Page 40
3.3.3 Conditional Probabilities......Page 41
3.3.4 Some prpoperties of Probability Dencities......Page 42
3.3.5 Particles in a Vessel......Page 44
3.4 Corelation Functions......Page 45
3.5 The Velocity of Space  and Time Dependent Stochastic Processes......Page 50
4.2 The Velocity Gradient......Page 59
4.7.3 \"Delusive\" Speckle Motion......Page 89
4.3  Motion of Particles in a Homogeneous Velocity Field......Page 60
4.5 Light Scattering by Particles......Page 65
4.6 The q-Volume of Coherence......Page 73
4.7.1 The motion of the Pattern......Page 81
4.7.2 The \"Boiling\" of the Speckle Pattern......Page 87
5.1 The Illuminating Laser Beam......Page 92
5.2 The Scattering Volume......Page 96
5.3 The Licht Scattering Particles......Page 98
5.5 Stray Light......Page 100
5.6 Test of the Set-Up......Page 101
5.7 Measurement of Quantities Varying Randomly in Time and Space......Page 102
5.8.1 The Connection between Pattern Velocity and k_o......Page 105
5.8.2 The Connection Between Gamma and k_o - An Example......Page 109
5.9.1 Measurement of Definite Cartesian Components......Page 112
5.9.2 Measurements of Wall Gradients......Page 114
5.10 General Notes to Channel Flows......Page 119
6.1.1 Introduction......Page 121
6.1.3 Scattering Geometry and Scattering Volume......Page 123
6.2.1 Experimental Set-Up......Page 124
6.2.2 Experimental Results......Page 125
7.1.1 Introduction......Page 127
7.1.2 The Demands on the Experimental Set-Up......Page 128
7.1.3 Evaluation Using Fit Procedures......Page 130
7.2.1 Experimental Set-Up......Page 131
7.2.2 Experimental Results......Page 132
8.1.2 The Admissible Size of the Recorded Speckle Pattern......Page 135
8.1.4 Oblique Speckle Motion and the Shape of the Scattering Volume......Page 136
8.1.5 Special Demands on the Optical Set-Up......Page 137
8.1.6 The Electronic Recording of the Speckle Pattern......Page 138
8.2 Experiments and Results......Page 139
8.2.2 Experimental Results......Page 140
9.1.1 Introduction......Page 144
9.1.2 Sample Time and Separation of the Detectors......Page 145
9.1.4 The Measurements of the Spatial Derivative of the Speckle Pattern......Page 146
9.1.5 The Temporal Integration of the Speckle Pattern......Page 148
9.1.6 The Size of the Scattering Volume and the Light Power Per Coherence Area......Page 149
9.1.8 Detectors and Signal Handling......Page 151
9.1.9 Detector Noise......Page 152
9.2.1 General Requirements for the Evaluation Algorithm......Page 153
9.2.2 Weight Function......Page 155
9.2.3 C-Method Algorithm......Page 156
9.2.4 S-Method Algorithm......Page 157
9.2.5 Limits of the method......Page 158
9.3.1 Tests of the Set-Up......Page 159
9.3.2 Results of Flow Measurements......Page 162
10.1.1 Introduction......Page 164
10.1.2 Symmetry Considerations......Page 166
10.1.3Exp erimental Considerations......Page 168
10.1.4 Data Evaluation......Page 170
10.2 Experiments and Results......Page 174
11. Outlook......Page 180
Bibliography......Page 182
Subject Index......Page 184