Mechanics of Wind-blown Sand Movements / Edition 1

Mechanics of Wind-blown Sand Movements / Edition 1

by Xiaojing Zheng
     
 

ISBN-10: 3540882537

ISBN-13: 9783540882534

Pub. Date: 05/01/2009

Publisher: Springer Berlin Heidelberg

This book systematically presents recent progress made in the research of aeolian processes, especially in the research on mechanism, theoretical modelling and computational simulation of aeolian processes from the viewpoint of mechanics.

Overview

This book systematically presents recent progress made in the research of aeolian processes, especially in the research on mechanism, theoretical modelling and computational simulation of aeolian processes from the viewpoint of mechanics.

Product Details

ISBN-13:
9783540882534
Publisher:
Springer Berlin Heidelberg
Publication date:
05/01/2009
Series:
Environmental Science and Engineering / Environmental Science Series
Edition description:
2009
Pages:
309
Product dimensions:
6.40(w) x 9.50(h) x 0.90(d)

Table of Contents

Chapter 1 Wind-Blown Sand Environment 1

1.1 Desert and Desertification 1

1.1.1 Desert 1

1.1.2 Desertification 4

1.2 Harms of Wind-Blown Sand Environment 6

1.2.1 Wind Erosion 7

1.2.2 Sand (Dust) Storm 8

1.3 Examples: Dunhuang, Minqin, Maqu 12

1.3.1 Dunhuang 12

1.3.2 Minqin 14

1.3.3 Maqu 16

Chapter 2 Flows of the Near-Surface Boundary Layer 19

2.1 An Introduction to Fluid Mechanics 19

2.1.1 Viscosity of a Fluid 20

2.1.2 Properties of Flow 20

2.2 Basic Equations of Fluid Mechanics 22

2.2.1 Conservation of Mass (Continuity Equation) 23

2.2.2 Conservation of Momentum 23

2.2.3 Conservation of Energy 24

2.2.4 Basic Equations of Turbulence 25

2.2.5 Models of Turbulence 25

2.2.6 Approaches of Turbulent Numerical Simulation 27

2.3 Basic Characteristics of the Atmospheric Boundary Layer 28

2.4 Observations of the Atmosphere Boundary Layer 32

2.5 Basic Equations of the Atmospheric Boundary Layer 38

2.5.1 Basic Equations 38

2.5.2 Aerodynamic Roughness 41

2.5.3 Characteristics of the Flow Field on the Wind-Blown Sand Boundary Layer 42

2.5.4 Effect of Sand Dunes on the Flow Field 44

2.6 Wind Gusts near the Earth's Surface 46

2.6.1 Analysis of the Wind Gusts 47

2.6.2 Prediction Model I: Wind Gusts Vary with Time 55

2.6.3 Prediction Model II: Wind Gusts Vary with Height 58

Chapter 3 Sand Motion near the Sand Bed Surface 61

3.1 Threshold Wind Velocity for Sand Motion 62

3.1.1 Mechanism of the Entrainment of Sand Particles 62

3.1.2 Threshold Wind Velocity of Sand Motion 63

3.1.3 Factors Affecting the Threshold Wind Velocity 65

3.2 Experimental Research on the Lift-off of Sand Particles 67

3.2.1 Experiments onParticle-Bed Collision with 'Artificial' Sand 67

3.2.2 Measurements of the Linear Velocities of Lift-off Particles 68

3.2.3 Measurement of the Angular Velocities of Saltating Particles 72

3.3 Stochastic Model of Particle-Bed Collision 76

3.3.1 Stochastic Model 76

3.3.2 Soft-Particle Approach for Collision Process 79

3.3.3 Hard-Particle Approach for Collision Process 81

3.3.4 Analytical Solution of Lift-off Velocity 84

3.4 Probability Distribution of Lift-off Velocities 86

3.5 Splash Function 94

3.5.1 Splash Function for 'Uniform' Sands 94

3.5.2 Splash Function for 'Mixed' Sands 98

Chapter 4 Wind-Blown Sand Electrification 105

4.1 Charged Sand Particles and their Charging Mechanisms 106

4.1.1 Observations and Measurements 106

4.1.2 Charging Mechanisms of Sand Particles 109

4.2 Measurements of Wind-Blown Sand Electric Field 111

4.2.1 Atmospheric Electric Field 111

4.2.2 Field Observation of Wind-Blown Sand Electric Field 112

4.2.3 Wind Tunnel Measurement of Wind-Blown Sand Electric Field 115

4.3 Theoretical Calculation of Wind-Blown Sand Electric Field 120

4.3.1 Electric Field Due to Sand Particles Moving in Air 121

4.3.2 Electric Field Due to Sand Particles in Sand Bed 122

4.3.3 Total Electric Field Due to Charged Sand Particles in Wind-Blown Sand Flux 123

4.4 Effects of Charged Sand Particles 126

4.4.1 Effects on the Entrainment of Sand Particles' 126

4.4.2 Effects on Electromagnetic Wave Propagation 128

Chapter 5 Wind-Blown Sand Flux and its Prediction 133

5.1 Forces on Saltating Sand Particles 134

5.2 Sand Saltation 139

5.2.1 The Effect of Wind-Blown Sand Electric Field on Sand Saltation 139

5.2.2 The Effects of Particle's Mid-Air Collisions on Sand Saltation Trajectories 144

5.2.3 Saltation Trajectory and Saltation Activity in a Fluctuating Wind Field 148

5.2.4 The Criterion of Saltation and Suspension 152

5.3 Experiments and Observations on Sand Transport Rate 155

5.4 Theoretical Simulations on the Evolution of Wind-Blown Sand Flux 160

5.5 Dust Devil 171

Chapter 6 Aeolian Geomorphology and its Simulation - Aeolian Sand Ripples 181

6.1 Observations of Aeolian Sand Ripples 183

6.1.1 The Basic Characteristics of Aeolian Sand Ripples 183

6.1.2 The Formation Mechanism of Aeolian Sand Ripples 187

6.2 Continuous Models for Aeolian Sand Ripples 189

6.2.1 The Anderson's Continuous Model 189

6.2.2 The Granular Surface Flow Model 192

6.3 Discrete Models for Aeolian Sand Ripples 196

6.3.1 Cellular Automata Model (Anderson-Bunas Discrete Model) 196

6.3.2 Discrete Element Model (Landry-Werner Model) 199

6.3.3 Coupled Mapping Lattice Model (Nishimori-Ouchi Model) 202

6.4 Discrete Particle Tracing Method (DPTM) Model 205

6.4.1 Basic Method 205

6.4.2 Major Simulation Results 207

Chapter 7 Aeolian Geomorphology and its Simulation - Aeolian Sand Dunes 219

7.1 Aeolian Sand Dunes and Observation Results 220

7.1.1 Classification of Sand Dunes 220

7.1.2 The Observation of Sand Dune Migration 225

7.1.3 Observation on the Dynamical Behavior of Sand Dunes 229

7.1.4 Influence Factors 231

7.2 Continuum Sand Dune Model 232

7.3 Simulation of Sand Dune Field 235

7.3.1 Coupled Mapping Lattice Method 235

7.3.2 Cellular Automaton Method 236

7.4 Numerical Simulation of Sand Dune Field 238

7.4.1 Discrete Numerical Simulation of Sand Dune Field 238

7.4.2 Simulation Results 243

Chapter 8 Mechanical Analysis on the Efficiency of Sand Prevention Methods 261

8.1 Sand Fence 262

8.2 Straw Checkerboard Barriers 268

8.3 The Mechanical Properties of Crust 272

8.3.1 The Survey on the Mechanical Properties of Crust 274

8.3.2 The Destruction of Saltating Sand to Crust 280

References 287

Author Index 301

Subject Index 305

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