Wind Flow and Vapor Cloud Dispersion at Industrial and Urban Sites (Ccps Concept Book)

a Key Component Of Risk Reduction Is Reducing The Potential Consequences That Could Result From Toxic Or Flammable Releases. The Science Of Vapor Cloud Dispersion Has Advanced Significantly In Recent Years, But One Of The Long-standing Challenges Has Been In Accounting For Dispersion Around Buildings, Equipment, And Similarly Sized Geologic And Man-made Features. With Current Concerns About Terrorism In Industrial And Urban Sites, Improving Consequence Modeling Within Industrial And Urban Sites Is More Important Than Ever This New Definitive Book Advances The Science Of Vapor Cloud Dispersion By: ·describing How Structures At An Urban Or Industrial Site Affect Dispersion, And How These Effects Should Be Treated In Consequence Models ·explaining Surface Roughness Length (z0) And Displacement Length (d) So That They Are Clarified For Readers With Minimal Meteorological Background ·presenting Criteria For When The Structures Should Be Considered Broadly As Roughness Elements, Or When They Should Be Considered From The Viewpoint Of Their Wake Effects ·defining Conditions For Which Different Models Apply And Providing Continuous Solutions For Transitions Between Flow Regimes. ·providing The Appropriate Roughness Inputs To Transport And Dispersion Models Depending On Conditions. ·demonstrating The Application Of These Techniques Through Worked Examples. booknews this Book Is Intended To Help Designers, Operators, And Emergency Response Officials Estimate The Effects Of On-site And Proximate Plant Structures, Process Equipment, And Buildings On The Transport And Dispersion Of Hazardous Materials. Chapters Cover Meteorology And Atmospheric Dispersion, Methods For Characterizing The Effects Of Surface Roughness, The Integration Of Roughness Into Dispersion Models, And Worked Examples For Seven Industrial And Urban Scenarios. The Worked Exercises Also Appear On A Companion Cd-rom. Hanna Is A Consultant. Britter Teaches At The University Of Cambridge. Annotation C. Book News, Inc., Portland, Or (booknews.com) cover.jpg......Page 1 Front Matter......Page 2 Preface......Page 4 Acknowledgments......Page 6 List of Symbols......Page 8 Glossary......Page 0 Table of Contents......Page 12 1.1 Background......Page 16 1.2 Objectives of This Book......Page 18 1.3 Overview......Page 19 1.4 Definition of Scenarios and Modeling Scales......Page 21 2. Overview of Meteorology and Atmospheric Dispersion......Page 23 2.1 Definitions of Concepts and Terms......Page 24 2.2 Engineering Background......Page 39 2.3.1 Introduction to Discussion of Effects of Surface Features......Page 43 2.3.2 Use of a Simple Gaussian Dispersion Model to Understand the Effects of Roughness......Page 45 2.3.3 Situations Where Winds, Stability and Underlying Terrain Vary in Time and/or Space......Page 47 2.3.4 Methods for Accounting for Surface Roughness Length and Displacement Length in Dispersion Models......Page 48 2.4.1 Dispersion of Clouds with Mass-Weighted Mean Heights Greater Than the Roughness Obstacle Height, Hr......Page 51 2.4.2 Dispersion of Clouds with Mass-Weighted Mean Heights Less Than the Roughness Obstacle Heights, Hr......Page 54 3. Methods for Characterizing the Effects of Surface Roughness Obstacles on Flow......Page 60 3.1 Required Flow Characteristics for Input to Transport and Dispersion Models......Page 61 3.2 Consideration of Flow Above and below the Tops of the Obstacles......Page 63 3.3 Flow Above the Surface Roughness Obstacles......Page 66 3.3.1 Definition of Surface Roughness Length, zo, and Displacement Length, d, as They Relate to Flow Characteristics Such as Wind Speed......Page 67 3.3.2 Methods for Estimating zo and d from Wind Observations......Page 69 3.3.3 Size of Surface Area That Influences Flow at a Given Height......Page 78 3.3.4 Estimation of zo and d Based on Knowledge of Surface Roughness Obstacles' Dimensions and Geometric Relations (The Morphological Method)......Page 81 3.3.5 Overview of Land Use Category Methods for Estimating zo and d......Page 92 3.3.6 Estimation of zo for Surface Conditions Varying in Space......Page 95 3.4 Flow through an Obstacle Array......Page 100 3.4.1 Extent of the Roughness Sublayer......Page 103 3.4.2 Wind Velocity Fields within and Near Obstacle Arrays......Page 104 3.4.3 Model Comparison with Experimental Data......Page 110 3.4.4 The Turbulence Field within the Obstacle Array......Page 112 3.4.5 Extensions to Other Effects within the Obstacle Array......Page 115 3.5 Summary of Recommended Methods for Estimating zo, d, Velocity (u*), and Turbulence Velocities in Urban and Industrial Areas and Flow Characteristics Such as Wind Profiles, Friction......Page 117 3.5.1 Definition of Region of Interest (from Source to Receptor)......Page 118 3.5.2 Determination of zo and d......Page 120 3.5.3 General Simple Formulas for u*, u(z), and Turbulent Velocities......Page 124 3.5.4 Selection of an Appropriate Mean Wind Speed and Stability......Page 125 3.5.5 Estimates of Urban and Industrial Geometric Parameters Hr, lambda f, and lambda p, Using the ROUGH Code......Page 126 3.5.6 Range of Uncertainty in Estimates of zo, d, u*, u(z), and Turbulent Velocities......Page 128 4.1 Objectives and Fundamental Physical Concepts......Page 130 4.2.1 Introduction to General Characteristics of Models......Page 134 4.2.2 Summary of Dispersion Experiments Over Rough Surfaces......Page 135 4.2.3 Gaussian Plume and Puff Model......Page 136 4.3 Dispersion Models for Clouds below Hr......Page 139 4.3.2 The Vertical Plume Dimension sigma z below Hr......Page 141 4.3.3 The Lateral Plume Dimension sigma y below Hr......Page 144 4.3.4 The Along-Wind Puff Dimension sigma x below Hr......Page 146 4.3.5 The Effect of uc, sigma x, sigma y and sigma z on the Concentration at Heights below Hr......Page 147 4.4 Transition Methods for Clouds of Height Close to Hr within the Urban Roughness Sublayer......Page 149 4.5.2 Dispersion Models for Clouds Released Above or Near Hr......Page 153 4.5.4 Dispersion Models for Scenarios Where the Upwind and Downwind Roughness Is Different......Page 154 4.5.5 Dispersion Models for Clouds Released Upwind of the Roughness and Traveling Into and through the Roughness......Page 155 5. Worked Examples of Calculations of Surface Roughness Length for Seven Industrial and Urban Scenarios......Page 156 5.1 Case 1: Small (18 m by 24 m) Industrial Plant......Page 157 5.2 Case 2: A Group of Industrial Warehouses Covering a 250 m by 250 m Area......Page 160 5.3 Case 3: Medium-Sized (400 m by 400 m) Refinery......Page 163 5.4 Case 4: Typical Urban Area (Chicago)......Page 166 5.5 Case 5: Industrial Plant (Case 3) in Chicago Urban Area......Page 168 5.6 Case 6: Industrial Plant from Case Located on a Peninsula......Page 172 5.7 Case 7: Large 4 km by 4 km Refinery in a Desert......Page 176 5.8 Summary of Seven Cases Used for Worked Examples......Page 178 Appendix: Text Files for CD-ROM with zo Estimation Codes......Page 180 ROUGH-GEOMETRY User's Guide......Page 183 ROUGH-ZO User's Guide......Page 191 References......Page 194 Glossary......Page 203 Index......Page 214