Incompressible Flow Third Edition Ronald L. Panton WILEY JOHN WILEY & SONS, INC. Contents Preface xi Preface to the Second Edition Preface to the First Edition 1 Continuum Assumption 3 Fundamental Concepts, Definitions, and Laws 3 Space and Time 5 Density, Velocity, and Internal Energy Interface between Phases 10 Conclusions 12 Problems 14 1.3 1.4 1.5 1.6 Thermodynamics 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 3.1 3.2 3.3 3.4 3.5 3.6 3.7 7 4 Kinematics of Local Fluid Motion 4.1 4.2 4.3 4.4 4.5 15 Systems, Properties, and Processes 15 Independent Variables 16 Temperature and Entropy 17 Fundamental Equations of Thermodynamics 18 Euler's Equation for Homogeneous Functions 19 Gibbs-Duhem Equation 20 Intensive Forms of Basic Equations 20 Dimensions of Temperature and Entropy Working Equations 21 Ideal Gas 22 Incompressible Substance 25 Conclusions 25 Problems 26 3 Vector Calculus and Index Notation Index Notation Rules 28 Definition of Vectors and Tensors 30 Special Symbols and Isotropic Tensors Direction Cosines and the Law of Cosines 32 Algebra with Vectors 33 Symmetric and Antisymmetric Tensors Algebra with Tensors 37 Vector Cross-Product 38 Alternative Definitions of Vectors and Tensors 40 Principal Axes and Values 41 Derivative Operations on Vector Fields Integral Formulas of Gauss and Stokes Leibnitz's Theorem 47 Conclusions 48 Problems 49 3.10 3.11 3.12 3.13 3.14 Continuum Mechanics 1.1 1.2 2 3.8 3.9 XUl 4.6 4.7 4.8 4.9 4.10 21 5 27 5.6 5.7 5.8 31 5.9 5.10 5.11 35 5.12 51 Lagrangian Viewpoint 51 Eulerian Viewpoint 54 Substantial Derivative 56 Decomposition of Motion 57 Elementary Motions in a Linear Shear Row 61 Proof of Vorticity Characteristics 64 Rate-of-Strain Characteristics 65 Rate of Expansion 66 Streamline Coordinates 67 Conclusions 69 Problems 69 Basic Laws 5.1 5.2 5.3 5.4 5.5 42 45 71 Continuity Equation 71 Momentum Equation 75 Surface Forces 76 Stress Tensor Derivation 76 Interpretation of the Stress Tensor Components 78 Pressure and Viscous Stress Tensor 80 Differential Momentum Equation 81 Moment of Momentum, Angular Momentum, and Symmetry of Ttj 85 Energy Equation 86 Mechanical and Thermal Energy Equations 89 Energy Equation with Temperature as the Dependent Variable 91 Second Law of Thermodynamics 91 vi Contents 5.13 5.14 Integral Form of the Continuity Equation 92 Integral Form of the Momentum Equation 94 Momentum Equation for a Deformable Particle of Variable Mass 97 Energy Equation in Integral Form 100 Jump Equations at Interfaces 101 Conclusions 102 Problems 102 5.15 5.16 5.17 5.18 8.11 9 Compressible Flow 9.1 9.2 9.3 6 Newtonian Fluids and the Navier-Stokes Equations 105 6.1 6.2 6.3 6.4 6.5 6.6 6.7 7 Newton's Viscosity Law 105 Molecular Model of Viscous Effects 108 Non-Newtonian Liquids 112 No-Slip Condition 115 Fourier's Heat Conduction Law 117 Navier-Stokes Equations 119 Conclusions 120 Problems 120 Some Incompressible Flow Patterns 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 121 Pressure-Driven Flow in a Slot 121 Mechanical Energy, Head Loss, and Bernoulli Equations 126 Plane Couette Flow 132 Pressure-Driven Flow in a Slot with a Moving Wall 133 Double Falling Film on a Wall 134 Outer Solution for Rotary Viscous Coupling 137 Rayleigh Problem 138 Conclusions 143 Problems 144 9.4 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 145 Measurement and Dimensions 145 Variables and Functions 147 Pi Theorem and Its Application 150 Pump or Blower Analysis: Use of Extra Assumptions 153 Number of Primary Dimensions 157 Proof of Bridgman's Equation 159 Proof of the Pi Theorem 161 Dynamic Similarity 164 Similarity with Geometric Distortion 165 Nondimensional Formulation of Physical Problems 168 175 Compressible Couette Flow: Adiabatic Wall 175 Flow with Power Law Transport Properties 178 Inviscid Compressible Waves: Speed of Sound 180 Conclusions 186 Problems 187 10 Incompressible Flow 188 10.1 10.2 Characterization 188 Incompressible Flow as Low-Mach-Number Flow with Adiabatic Walls 189 10.3 Nondimensional Problem Statement 191 10.4 Characteristics of Incompressible Flow 195 10.5 Splitting the Pressure into Kinetic and Hydrostatic Parts 197 10.6 Mathematical Aspects of the Limit Process M2 — 0 200 10.7 Invariance of Incompressible Flow Equations under Unsteady Motion 201 10.8 Low-Mach-Number Flows with ConstantTemperature Walls 203 10.9 Energy Equation Paradox 206 10.10 Conclusions 208 Problems 208 11 11.1 8 Dimensional Analysis Conclusions 173 Problems 173 Some Solutions of the Navier-Stokes Equations 210 Pressure-Driven Flow in Tubes of Various Cross Sections: Elliptical Tube 211 11.2 Flow in a Rectangular Tube 213 11.3 Channel with Longitudinal Ribs 216 11.4 Stokes's Oscillating Plate 218 11.5 Wall under an Oscillating Free Stream 221 11.6 Transient for a Stokes Oscillating Plate 224 11.7 Flow in a Slot with a Steady and Oscillating Pressure Gradient 226 11.8 Decay of an Ideal Line Vortex (Oseen Vortex) 230 11.9 Plane Stagnation-Point Flow (Hiemenz Flow) 235 11.10 Burgers Vortex 241 11.11 Complete Solution for Rotary Coupling 242 Contents 11.12 Von Karman Viscous Pump 11.13 Conclusions 248 Problems 249 244 12 Streamfunctions and the Velocity Potential 251 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 Streamlines 251 Streamfunction for Plane Flows 254 Flow in a Slot with Porous Walls 256 Streamlines and Streamsurfaces for a ThreeDimensional Flow 259 Vector Potential and the E2 Operator 262 Velocity Potential and the Unsteady Bernoulli Equation 266 Flow Caused by a Sphere with Variable Radius 267 Conclusions 269 Problems 270 13 Vorticity Dynamics 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 13.10 13.11 13.12 13.13 13.14 13.15 271 Vorticity 271 Kinematic Results Concerning Vorticity 272 Vorticity Equation 274 Vorticity Diffusion 275 Vorticity Intensification by Straining Vortex Lines 277 Hill's Spherical Vortex 278 Production of Vorticity at a Stationary Wall 280 Production of Vorticity at a Translating Wall 282 Helmholtz's Laws for Inviscid Flow 284 Kelvin's Theorem 285 Inviscid Motion of Point Vortices 286 Reconnection of Vortex Lines 288 Development of Typical Vorticity Distributions 288 Vortex Breakdown 294 Conclusions 298 Problems 299 14 Flows at Moderate Reynolds Numbers 300 14.1 14.2 14.3 Some Unusual Flow Patterns 301 Entrance Flows 303 Entrance Flow into a Cascade of Plates: Computer Solution by the StreamfunctionVorticity Method 305 14.4 14.5 14.6 14.7 14.8 14.9 15 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9 16 16.1 16.2 16.3 16.4 16.5 17 17.1 17.2 17.3 17.4 17.5 Entrance Flow into a Cascade of Plates: Pressure Solution ,313 Entrance Flow into a Cascade of Plates: Results 316 Flow around a Circular Cylinder 320 Jeffrey-Hamel Flow in a Wedge 336 Limiting Cases for Re —» 0 and Re —» -oo 340 Conclusions 344 Problems 345 Asymptotic Analysis Methods 347 Oscillation of a Gas Bubble in a Liquid 347 Order Symbols, Gauge Functions, and Asymptotic Expansions 350 Inviscid Flow over a Wavy Wall 353 Nonuniform Expansions: Friedrich's Problem 356 Matching Process: Van Dyke's Rule 358 Composite Expansions 363 Characteristics of Overlap Regions 365 Lagerstrom's Problems 370 Conclusions 374 Problems 374 Characteristics of High-Reynolds-Number Flows 376 Physical Motivation 376 Inviscid Main Flows: Euler Equations 378 Pressure Changes in Steady Rows: Bernoulli Equations 381 Boundary Layers 385 Conclusions 395 Problems 395 Kinematic Decomposition of Flow Fields 396 General Approach 396 Helmholtz's Decomposition 397 Line Vortex and Vortex Sheet 398 Complex Lamellar Decomposition 401 Conclusions 404 Problems 404 18 Ideal Flows in a Plane 18.1 vii 405 Problem Formulation for Plane Ideal Flows 406 viii Contents 18.2 18.3 18.4 18.5 18.6 18.7 18.8 18.9 18.10 18.11 18.12 18.13 18.14 18.15 18.16 18.17 18.18 18.19 Simple Plane Flows 409 Line Source and Line Vortex 412 Flow over a Nose or a Cliff 414 Doublets 420 Cylinder in a Stream 422 Cylinder with Circulation in a Uniform Stream 424 Lift and Drag on Two-Dimensional Shapes 426 Magnus Effect 429 Conformal Transformations 431 Joukowski Transformation: Airfoil Geometry 434 Kutta Condition 439 Flow over a Joukowski Airfoil: Airfoil Lift 442 Numerical Method for Airfoils 448 Actual Airfoils 451 Schwarz-Christoffel Transformation 453 Diffuser or Contraction Flow 455 Gravity Waves in Liquids 460 Conclusions 465 Problems 466 20.3 20.4 20.5 20.6 20.7 20.8 20.9 20.10 20.11 20.12 20.13 20.14 20.15 20.16 20.17 20.18 20.19 20.20 20.21 20.22 19 Axisymmetric and Three-Dimensional Ideal Flows 468 19.1 19.2 19.3 19.4 19.5 19.6 19.7 19.8 19.9 19.10 19.11 19.12 19.13 19.14 20 20.1 20.2 General Equations and Characteristics of Three-Dimensional Ideal Flows 468 Swirling Flow Turned into an Annulus 470 Flow over a Weir 471 Point Source 473 Rankine Nose Shape 474 Experiments on the Nose Drag of Slender Shapes 477 Flow from a Doublet 478 Flow over a Sphere 481 Kinetic Energy 483 Wake Drag of Bodies 484 Induced Drag: Drag due to Lift 486 Lifting Line Theory 490 Added Mass of Accelerating Bodies 491 Conclusions 496 Problems 496 Boundary Layers 498 Blasius Flow over a Flat Plate Displacement Thickness 503 498 Von Karma'n Momentum Integral 505 Von Karman-Pohlhausen Approximate Method 506 Falkner-Skan Similarity Solutions 508 Arbitrary Two-Dimensional Layers: CrankNicolson Difference Method 513 Vertical Velocity 521 Joukowski Airfoil Boundary Layer 524 Boundary Layer on a Bridge Piling 527 Boundary Layers Beginning at Infinity 530 Plane Boundary Layer Separation 535 Axisymmetric Boundary Layers 537 Jets 540 Far Wake of Nonlifting Bodies 543 Free Shear Layers 546 Unsteady and Erupting Boundary Layers 548 Entrance Flow into a Cascade 551 Three-Dimensional Boundary Layers 553 Boundary Layer with a Constant Transverse Pressure Gradient 557 Howarth's Stagnation Point 561 Three-Dimensional Separation 564 Conclusions 568 Problems 568 21 Flows at Low Reynolds Numbers 21.1 21.2 21.3 21.4 21.5 21.6 21.7 21.8 21.9 21.10 21.11 21.12 21.13 21.14 571 General Relations for Re - • 0: Stokes's Equations 571 Global Equations for Stokes Flow 574 Streamfunction for Plane and Axisymmetric Flows 577 Internal Flows: Plane 579 Internal Flows: Three-Dimensional and Axisymmetric 587 Local Flows: Plane (Moffatt Vortices) 591 Local Flows: Axisymmetric 596 External Flow: Sphere in a Uniform Stream 599 Composite Expansion for Flow over a Sphere 604 Stokes Flow near a Circular Cylinder 605 Axisymmetric Particles 606 Oseen's Equations 608 Interference Effects 609 Conclusions 611 Problems 611 Contents 22 Lubrication Approximation 22.1 22.2 22.3 22.4 22.5 22.6 22.7 613 25.3 Basic Characteristics: Channel Flow 613 Flow in a Channel with a Porous Wall 616 Reynolds Equation for Bearing Theory 618 Slipper Pad Bearing 620 Squeeze-Film Lubrication: Viscous Adhesion 622 Journal Bearing 623 Conclusions 627 Problems 627 23 Surface Tension Effects 629 23.1 23.2 23.3 23.4 23.5 Interface Concepts and Laws 629 Statics: Plane Interfaces 636 Statics: Cylindrical Interfaces 639 Statics: Attached Bubbles and Drops 641 Constant-Tension Rows: Bubble in an Infinite Stream 643 23.6 Constant-Tension Flows: Capillary Waves 646 23.7 Moving Contact Lines 648 23.8 Constant-Tension Flows: Coating Flows 651 23.9 Marangoni Flow 656 23.10 Conclusions 665 Problems 665 24 Introduction to Microflows 24.1 24.2 24.3 24.4 24.5 24.6 24.7 24.8 24.9 24.10 24.11 667 Molecules 667 Continuum Description 669 Compressible Flows in Long Channels Simple Solutions with Slip 673 Gases 676 Couette Flow in Gases 680 Poiseuille Row in Gases 682 Gas Row over a Sphere 687 Liquid Rows in Tubes and Channels Liquid Rows near Walls 692 Conclusions 697 25 Introduction to Stability and Transition 698 25.1 25.2 Linear Stability and Normal Modes as Perturbations 699 Kelvin-Helmholtz Inviscid Shear Layer Instability 700 670 690 25.4 25.5 25.6 25.7 25.8 25.9 25.10 25.11 25.12 25.13 25.14 25.15 25.16 ix Stability Problem for Nearly Parallel Viscous Rows 704 Orr-Sommerfeld Equation 707 Inviscid Stability of Nearly Parallel Rows 708 Viscous Stability of Nearly Parallel Rows 709 Experiments on Blasius Boundary Layers 712 Transition, Secondary Instability, and Bypass 714 Spatially Developing Open Rows 719 Transition in Free Shear Rows 719 Poiseuille and Plane Couette Rows 721 Inviscid Instability of Rows with Curved Streamlines 723 Taylor Instability of Couette Row 725 Stability of Regions of Concentrated Vorticity 727 Other Instabilities: Taylor, Curved Pipe, Capillary Jets, and Gortler 728 Conclusions 731 26 Introduction to Turbulent Flows 732 26.1 26.2 26.3 26.4 26.5 26.6 26.7 26.8 26.9 26.10 Types of Turbulent Flows 732 Characteristics of Turbulent Rows 733 Reynolds Decomposition 736 Reynolds Stress 737 Free Turbulence: Plane Shear Layers 740 Free Turbulence: Turbulent Jet 741 Bifurcating and Blooming Jets 747 Correlations of Ructuations 747 Mean and Turbulent Kinetic Energy 750 Energy Cascade: Kolmogorov Scales and Taylor Microscale 752 26.11 Wall Turbulence: Channel Flow Analysis 756 26.12 Wall Layers: Experiments and Empirical Correlation 764 26.13 Turbulent Structures 768 26.14 Conclusions 773 A Properties of Fluids 775 B Differential Operations in Cylindrical and Spherical Coordinates 776 x Contents Basic Equations in Rectangular, Cylindrical, and Spherical Coordinates 781 D Streamfunction Relations in Rectangular, Cylindrical, and Spherical Coordinates 786 E Computer Code for Entrance Flow into a Cascade 790 F Computer Code for Boundary Layer Analysis 793 References 796 Index 813