Progress in Turbulence III: Proceedings of the iTi Conference in Turbulence 2008 (Springer Proceedings in Physics (131))

This third issue on “progress in turbulence” is based on the third ITI conference (ITI interdisciplinary turbulence initiative), which took place in Bertinoro, North Italy. Researchers from the engineering and physical sciences gathered to present latest results on the rather notorious difficult and essentially unsolved problem of turbulence. This challenge is driving us in doing basic as well as applied research. Clear progress can be seen from these contributions in different aspects. New - phisticated methods achieve more and more insights into the underlying compl- ity of turbulence. The increasing power of computational methods allows studying flows in more details. Increasing demands of high precision large turbulence - periments become aware. In further applications turbulence seem to play a central issue. As such a new field this time the impact of turbulence on the wind energy conversion process has been chosen. Beside all progress our ability to numerically calculate high Reynolds number turbulent flows from Navier-Stokes equations at high precision, say the drag co- ficient of an airfoil below one percent, is rather limited, not to speak of our lack of knowledge to compute this analytically from first principles. This is rather - markable since the fundamental equations of fluid flow, the Navier-Stokes eq- tions, have been known for more than 150 years. Title Page Preface Contents Turbulence Fully Developed Turbulence with Diminishing Mean Vortex Stretching and Reduced Intermittency References Spectral and Physical Forcing of Turbulence Introduction Stochastic and Linear Forcing Results and Discussion Conclusion References Fractal-Generated Turbulent Scaling Laws from a New Scaling Group of the Multi-Point Correlation Equation Multi-Point Equation in the Limit of Homogeneous Turbulence Symmetries of the Multi-Point Equation Invariant Solutions and Turbulent Decay Scaling Laws Conclusions References Investigation of the Conditional Scalar Dissipation Rate Across a Shear Layer Using Gradient Trajectories Introduction Results Conclusions References ‘Rational’ Turbulence Models? Models for Homogeneous Isotropic Turbulence Models for Inhomogeneous Turbulence References An Approximation of the Invariant Measure for the Stochastic Navier-Stokes Introduction Fluid Flow and Ito Diffusion The Approximation References Spatial Multi-Point Correlations in Inhomogeneous Turbulence Introduction – Closure Problem and Stochastic Processes Experimental Results – Markov Properties References Statistical Properties of Velocity Increments in Two-Dimensional Turbulence Introduction Numerical Treatment and Statistical Analysis Conclusion References Enstrophy Transfers Study in Two-Dimensional Turbulence The Interaction Function Experimental Setup and Numerical Results Conclusion References Two Point Velocity Difference Scaling along Scalar Gradient Trajectories in Turbulence Introduction Theory and Results Conclusions References Stochastic Analysis of Turbulence n-Scale Correlations in Regular and Fractal-Generated Turbulence Introduction Results for Fractal-Generated Turbulence References Experimental Methods Holographic PIV with Low Coherent Light – Recent Progress in 3D Flow Measurements Principles of Holographic PIV Noise Problem and Light-in-Flight Configuration Measurements Conclusions References An Experimental Demonstration of Accelerated Tomo-PIV Introduction An Experimental Assessment of Accelerated Tomo-PIV Conclusions References Using the 2D Laser-Cantilever-Anemometer for Two-Dimensional Measurements in Turbulent Flows LCA - Basic Principle Development of the 2D LCA Measurements with 2DLCA and x-Wire Conclusions Reference 3D Structures from Stereoscopic PIV Measurements in a Turbulent Boundary Layer Introduction Experiment Results Summary References The Sphere Anemometer – A Fast Alternative to Cup Anemometry Sphere Anemometer Principle and Setup Measurements Conclusions References CICLoPE – A Large Pipe Facility for Detailed Turbulence Measurements at High Reynolds Number Fully Resolved High Reynolds Number Experiment The Long Pipe Facility at CICLoPE The CICLoPE Laboratory References Wind Energy Aerodynamics of an Airfoil at Ultra-Low Reynolds Number Introduction Experimenral Details Results and Discussion Conclusion References Turbulence Energetics in Stably Stratified Atmospheric Flows Energy and Flux Budget Turbulence Closure Model Effect of Large-Scale Internal GravityWaves Conclusions References Measurements of the Flow Upstream a Rotating Wind Turbine Model Introduction Experimental Conditions Results References Is the Meandering of aWind TurbineWake Due to Atmospheric Length Scales? Introduction Experimental Set Up Analysis Temporal Study Spatial study Conclusion References Impact of Atmospheric Turbulence on the Power Output ofWind Turbines Introduction Characterization of Turbulent Structures Stochastic RelaxationModel Discussion and Concluding Remarks References About First Order Geometric Auto Regressive Processes for Boundary Layer Wind Speed Simulation Motivation Fluctuation Statistics Increment Statistics Summary References Unsteady Numerical Simulation of the Turbulent Flow around a Wind Turbine Introduction Configuration and Investigated Flow Case Unsteady Numerical Simulation of the Blade Flow Conclusion References A New Non-gaussian TurbulentWind Field Generator to Estimate Design-Loads of Wind-Turbines Introduction Model Description Wind-Field Models Wind Turbine Model Result: Blade-Root Bending Moment Summary and Conclusions References Synthetic Turbulence Models for Wind Turbine Applications Introduction Overview over Existing Models Spectral Models (Category I) Improvements of Spectral Models (Categories II-IV) Probabilistic CTRW-Model (Category V) Modelling of Energy Cascade (Categories VI and VII) Multi-scale Reconstruction of Time Series (Category VIII) Summary References Numerical Simulation of the Flow around a Tall Finite Cylinder Using LES and PANS Description of the Set-Up and Numerical Methods Results References Large Eddy Simulation of Turbulent Flows around a Rotor Blade Segment Using a Spectral Element Method Introduction Results of LES for $Re$ = 5 ·10\^{3} and $Re$ = 5 ·10\^{4} References Modelling and Simulation and Mathematics Vorticity and Helicity in Swirling Pipe Flow Introduction Results Conclusions References Explicit Algebraic Subgrid Models for Large Eddy Simulation Model Description Validation References Direct Numerical Simulation of a Turbulent Flow with Pressure Gradients Introduction Computational Details Results and Discussion References An Invariant Nonlinear Eddy Viscosity Model Based on a Consistent 4D Modelling Approach Introduction Construction of a Newtonian Space-Time Manifold Proposal for an Invariant Nonlinear Eddy Viscosity Model References A Hybrid URANS/LES Approach Used for Simulations of Turbulent Flows Introduction Problem Formulation Results Conclusion References Anisotropic Synthetic Turbulence with Sweeping Generated by Random Particle-Mesh Method Introduction Convective Moving-Average Method Numerical Results Conclusion References LES and Hybrid LES/RANS Study of Flow and Heat Transfer around aWall-Bounded Short Cylinder Introduction Models and Numerics Discussion Conclusions References Stochastically Forced Laminar Plane Couette Flow: Non-normality and Hydrodynamic Fluctuations Introduction DNS of the Stochastically Forced Plane Couette Flow Results References Reynolds Stress Model Based on the RDT Equations and Turbulence Dynamics in the Aerodynamic Nozzle The Paradigm of the Turbulence Model Turbulence in Nozzles References Particle Laden Flows Heat Transfer Modulation by Microparticles in Turbulent Channel Flow Introduction DNS/LPT Methodology Results and Discussion References Particle Diffusion in Stably Stratified Flows Introduction Numerical Simulations and Results References Anisotropic Clustering of Inertial Particles in Shear Turbulence Motivation and Results References Spatial Evolution of Inertial Particles in a Turbulent Pipe Flow Instantaneous Visualization Particles Concentration and Shannon Entropy References Direct Numerical Simulation of Particle Interaction with Coherent Structures in a Turbulent Channel Flow Introduction Results Conclusions References Convection and Boundary Layer Asymmetries in Turbulent Rayleigh-B\'{e}nard Convection Introduction Experimental Results References LES of Riblet Controlled Temporal Transition of Channel Flow Introduction Results References Evolution of a Boundary Layer from Laminar Stagnation-Point Flow towards Turbulent Separation Motivation and Problem Formulation Asymptotic Analysis Numerical Results Conclusions and Further Outlook References The Response of Wall Turbulence to Streamwise-Traveling Waves of Spanwise Velocity Background Numerical Details Drag Reduction and Energy Savings The Laminar Generalized Stokes Layer References Dynamics of ViscoelasticWall Turbulence in Different Ranges of Scales Introduction Small Scale Dynamics and Energy Containing Scales Comments and Remarks References Hairpin Structures in a Turbulent Boundary Layer under Stalled-Airfoil-Type Flow Conditions Introduction Results and Discussion References Signature of VaricoseWave Packets in the Viscous Sublayer Introduction References Special Flows Entrainment Reduction and Additional Dissipation in Dilute Polymer Solutions Introduction Experimental Method Results and Discussion References Mixing at the External Boundary of a Submerged Turbulent Jet Experimental Set-Up Theoretical Modelling of Turbulent Mixing and Comparison with Experiments Conclusions References Turbulence in Electrically Conducting Fluids Driven by Rotating and Travelling Magnetic Fields Introduction Numerical Method Results and Outlook References The Decay of Turbulence in Pipe Flow Introduction Lifetimes Results References The Effect of Spanwise System Rotation on Turbulent Poiseuille Flow at Very-Low-Reynolds Number Introduction Numerical Methods Results and Discussion Conclusions References LES of the Flow over a High-Lift Airfoil Configuration Introduction Numerical Method and Computational Setup Results References The Effect of ObliqueWaves on Jet Turbulence Introduction Experimental Set-Up Results, Discussion and Conclusions References Turbulence Enhancement in Coaxial Jet Flows by Means of Vortex Shedding Introduction Experimental Arrangement Results Conclusions References Direct Numerical Simulation of Microbubble Dispersion in Vertical Turbulent Channel Flow Introduction Results and Discussion References Experimental and Numerical Analysis of the Stability of the VerticalWater Jet with Rectangular Cross Section Introduction Experimental Set-Up Measurement Results and Numerical Simulations Conclusions References Control of Separated Flow Using an Oscillating Lorentz Force: Comparison of DNS, LES, and Experiments Introduction Setup Results References Study of Effects of Wall-Normal Rotation on the Turbulent Channel Flow Using DNS Introduction DNS of Turbulent Wall-Normal Rotating Channel Flow Conclusion References Vortex A Langevin Equation for the Turbulent Vorticity Kinetic Theory for the Turbulent Vorticity Numerical Results Discussion References Application of Helical Characteristics of the Velocity Field to Evaluate the Intensity of Tropical Cyclones Brief History of the Problem Helicity Flux as a Measure of Tropical Cyclone Intensity: Theoretical Ground Calculations of Helicity Index for Tropical Cyclones References An Experimental Study of Turbulent Vortex Rings Introduction The Experiment Results Turbulence in and Around Core Area Three Dimensional Structure Construction Conclusion References Author Index This third issue on "progress in turbulence" is based on the third ITI conference (ITI interdisciplinary turbulence initiative), which took place in Bertinoro, North Italy. Researchers from the engineering and physical sciences gathered to present latest results on the rather notorious difficult and essentially unsolved problem of turbulence. This challenge is driving us in doing basic as well as applied research. Clear progress can be seen from these contributions in different aspects. New sophisticated methods achieve more and more insights into the underlying complexity of turbulence. The increasing power of computational methods allows studying flows in more details. Increasing demands of high precision large turbulence experiments become aware. In further applications turbulence seem to play a central issue. As such a new field this time the impact of turbulence on the wind energy conversion process has been chosen. The structure of the present book is as such that contributions have been bundled according to covering topics i.e. I Turbulence, II Experimental Methods, III Wind Energy, IV Modeling & Simulation & Mathematics, V Particle Laden Flows, VI Convection & Boundary Layer, VII Special Flows and VIII Vortex