Advances in critical flow dynamics involving moving/deformable structures with design applications : proceedings of the IUTAM Symposium on Critical Flow Dynamics Involving Moving/Deformable Structures with Design Applications, June 18-22, 2018, Santorini,

This book reports on the latest knowledge concerning critical phenomena arising in fluid-structure interaction due to movement and/or deformation of bodies. The focus of the book is on reporting progress in understanding turbulence and flow control to improve aerodynamic / hydrodynamic performance by reducing drag, increasing lift or thrust and reducing noise under critical conditions that may result in massive separation, strong vortex dynamics, amplification of harmful instabilities (flutter, buffet), and flow -induced vibrations. Theory together with large-scale simulations and experiments have revealed new features of turbulent flow in the boundary layer over bodies and in thin shear layers immediately downstream of separation. New insights into turbulent flow interacting with actively deformable structures, leading to new ways of adapting and controlling the body shape and vibrations to respond to these critical conditions, are investigated. The book covers new features of turbulent flows in boundary layers over wings and in shear layers immediately downstream: studies of natural and artificially generated fluctuations; reduction of noise and drag; and electromechanical conversion topics. Smart actuators as well as how smart designs lead to considerable benefits compared with conventional methods are also extensively discussed. Based on contributions presented at the IUTAM Symposium “Critical Flow Dynamics involving Moving/Deformable Structures with Design applications”, held in June 18-22, 2018, in Santorini, Greece, the book provides readers with extensive information about current theories, methods and challenges in flow and turbulence control, and practical knowledge about how to use this information together with smart and bio-inspired design tools to improve aerodynamic and hydrodynamic design and safety. Preface Contents Flow Induced Vibrations Alteration of the Spanwise Structure of the Turbulent Flow Past a Cylinder Subjected to Vortex-Induced Vibrations 1 Introduction 2 Method 3 Results References Vortex-Induced Vibration of Symmetric Airfoils Used in Vertical-Axis Wind Turbines 1 Introduction 2 Experimental Setup and Results 2.1 Experimental Setup 2.2 An Overall View of the Response 2.3 Sample Cases and the Higher Harmonic Contributions 2.4 The Wake Pattern 3 Conclusions References Flow Past an Oscillating Cylinder: Effects of Oscillation Mode on Wake Structure 1 Introduction 2 Formulation and Numerical Method 3 Results 4 Conclusions References Numerical Simulation of Oscillating Vibrating Flow Around Bodies Turbulent Backward-Facing Step Flow: Reliability Assessment of Large-Eddy Simulation Using ILSA 1 Introduction 2 Reliability Issues in Large-Eddy Simulation 3 ILSA—Integral Length-Scale Approximation 4 Local ILSA for Flow Over a Backward-Facing Step 5 Concluding Remarks References Hydrodynamics of Cylinders Oscillating with Small Amplitude in Still Fluid or Free Stream 1 Introduction 2 Methodology 3 Results and Discussion 3.1 Instantaneous Flow Patterns and Distributions 3.2 Time-Histories of Forces 4 Concluding Remarks References Validation of Coupled CFD-CSM Methods for Vibration Phenomena in Nuclear Reactor Cores 1 Introduction 2 Vattenfall Rod Vibration Experiment 2.1 Experimental Facility and Instrumentation 2.2 Experimental Test Cases 3 CFD-CSM Multiphysics Simulation Methods 4 Modal Analysis with ANSYS Mechanical 5 Model Development and Boundary Conditions 5.1 CFD-CSM Model 5.2 Simulation Setup and Boundary Conditions 6 Simulation Results 6.1 Analysis 6.2 Possible Explanations for the Observed Results 7 Conclusions References Fluid Structure Interaction Arising in Aerodynamics and Flow Control Control of Cellular Separation Using Adaptive Surface Structures 1 Introduction 2 Experimental Setup 3 Key Results 3.1 Surface Skin Friction 3.2 Surface Pressure Spectra 3.3 Modal Decomposition of Velocity Field 4 Conclusions Vibration Mechanism of Two Inline Cylinders 1 Introduction 2 Experimental Setup 3 Results and Discussions 3.1 Vibration Response 3.2 Galloping Vibration Generation Mechanism at Regime I 3.3 Galloping Vibration Generation Mechanism at Regime III 4 Conclusions References Experimental and Numerical Investigation of Steady Fluid Forcespg in Axial Flow on a Cylinder Confinedpg in a Cylinder Array 1 Introduction 2 Experimental Apparatus and Numerical Model 2.1 A Wind Tunnel Test Rig 2.2 RANS Simulations 3 Taylor-Lighthill-Païdoussis Model of Fluid Forces 4 Results and Discussion 4.1 Rotation 4.2 Translation 5 Conclusions References Numerical Investigation on the Thrust Performance of Bionic Motion Wing in Schools 1 Introduction 2 Numerical Methodology and Solver Accuracy Validation 2.1 Numerical Method 2.2 Solver Accuracy Validation 3 Problem Descriptions 3.1 3D Multi-bionic Wing Math Model 3.2 Grid Independence Validation 3.3 Time Independence Validation 4 Numerical Simulations and Discussions 5 Conclusions References Stress Analysis of Wind Turbine Tower Flange Using Fluid-Structure Interaction Method 1 Introduction 2 Numerical Analysis 2.1 Model Description 2.2 Grid Systems 3 One-Way Fluid-Structure Analysis 4 Structural Stability Evaluation 5 Conclusions References The Dynamics of Bumblebee Wing Pitching Rotation: Measurement and Modelling 1 Introduction 2 Kinematic Reconstruction 3 Numerical Modelling 4 Conclusions References Transitional Flow Dynamics Past a Passively Flapping Airfoil in Gusty Flow 1 Introduction 2 Governing Equations and Computational Details 3 Results and Discussions 3.1 Effect of Time-Harmonic Gust 3.2 Intermittent Flow Dynamics 3.3 Effect of Random Gust 4 Concluding Remarks References Theoretical Aspects, Simulation and Reduced-Order Modelling of Fluid-Structure Interaction for Deformable Structures Using Multicompartmental Poroelasticity to Explore Brain Biomechanics and Cerebral Diseases 1 Introduction 2 Methodology 2.1 Multiple-Network Poroelastic Theory (MPET) 2.2 Three-Dimensional MPET Model for the Cerebral Environment 2.3 MPET Verification and Mesh Independence 2.4 Subject-Specific Datasets 2.5 Subject-Specific Boundary Conditions and Parameters 2.6 Cerebral Ventricles Volume Extraction and Discretization 3 Consolidated Modelling Pipeline for the Cerebral Environment 4 Results and Discussion 5 Conclusions References The Shearing Mechanism Over a Deformed Surface of Breaking Waves 1 Introduction 2 Theory 3 Results References Flag Flutter Close to a Free Surface: A Local Stability Analysis 1 Introduction 2 Problem Setting 3 Analysis of Fluid Loading Function f 3.1 Unconfined Case (Large-h Limit) 3.2 Rigid Confinement (Small-Fr Limit) 3.3 Free Surface Effects 4 Stability Results 4.1 Confinement Versus Free Surface 4.2 Free Surface-Induced Instability 4.3 Mode Structure 5 Conclusion References FSI Simulation Using a Membrane Model: Inflation of Balloons and Flow Past Sails 1 Introduction 2 Problem Formulation 3 Computational Method 4 Results and Discussion 4.1 Inflation of a Balloon 4.2 Flow Past a Square Membrane 5 Conclusion References Numerical Simulation on a Fixed Mesh for the Feedback Stabilization of a Fluid–Structure Interaction System with a Structure Given by a Finite Number of Parameters 1 Introduction 1.1 Position of the Problem 1.2 Previous Work 1.3 Outline 2 Setting of the Problem and Modelling of the Deformation 2.1 The Fluid–Structure Model 2.2 The Diffeomorphisms Used to Model the Deformation of the Structure Given by a Finite Number of Parameters 3 Stabilization of the Linear Problem 4 The Discretization and Time Evolution of the Fluid–Structure System 4.1 Fluid Approximation: Unfitted Extended Finite Element Method with Lagrange Multipliers 4.2 Structure Approximation 4.3 Coupling Scheme 4.4 Fictitious Points and Level-Set Update 4.5 Computation of the Feedback Control in the Actual Domain 5 Numerical Results References Studying the Transition in the Flow Around a Cylinder Using a Low Dimensional Model and Sensitivity Analysis 1 Introduction 2 Theoretical Formulation of the Reduced Model 2.1 Fourier Modes Decomposition 2.2 Calculation of the Sensitivity Field mathcal 2.3 Building the Reduced Space 2.4 Hydrodynamic Fields and Forces 3 Conclusion References Reduced Order Modeling for Plasma Aeroelastic Control of Airfoils in Cascade: Dynamic Mode Decomposition 1 Introduction 2 Computational Fluid Dynamic Assessments 2.1 Baseline Flow with and Without Plasma Actuation 2.2 Reference Numerical Results with and Without Plasma Actuation 3 Overview on the Dynamic Mode Decomposition 4 Results 5 Conclusions References Dynamic Behavior of Leading Edge Vortex and Vorticity on Suction Surface of a Heaving Elastic Airfoil 1 Introduction 2 Fluid Structure Interaction Simulation 2.1 Airfoil Model 2.2 Fluid Structure Interation Simulation 3 Results and Discussion 3.1 Dynamic Behaviors of Leading Edge Vortex 3.2 Growth of Vorticity in Vicinity of Wall 4 Conclusions References Studying Sound Production in the Hole-Tone Configuration Using Compressible and Incompressible Global Stability Analyses 1 Introduction 2 Geometry Configuration and Governing Equations 3 Global Stability Approach 3.1 Incompressible Analysis 3.2 Modeling the Effect of Compressibility of the Cavity in an "Augmented Incompressible Approach" 3.3 Full Compressible Approach 4 Numerical Methods 5 Results 5.1 Incompressible Results 5.2 Effect of Compressibility 5.3 An Example of Practical Application 6 Conclusions References Rotating Effects, Fish Motion, Swimmers, Energy Harvesting Simultaneous Energy Harvesting Using Dual Piezo-Solar Devices 1 Introduction 2 Materials and Methods 2.1 Piezo-Solar Harvesters 2.2 Experimental Setup 2.3 Numerical Solver 3 Results 3.1 Flag Dynamics 3.2 Power Generation 3.3 Numerical Simulations 4 Discussion and Conclusions References Hydrokinetic Energy Conversion Using a Single-Cylinder Nonlinear Oscillator in Flow Induced Oscillations 1 Introduction 2 Physical Model and Nonlinear Oscillator 3 Mathematical Model 4 Results and Discussion 4.1 Response of Converter with Noinlinear Oscillators 4.2 Harnessed Power and Efficiency 5 Conclusions References Synergistic Flow Induced Oscillations of Multiple Cylinders in Harvesting Marine Hydrokinetic Energy 1 Introduction 2 Physical Model and the Virtual Controller 3 Mathematical Model 4 Results and Discussion 4.1 Harnessed Power and Efficiency of the Two-Cylinder Converter 4.2 Oscillatory Response, Power and Efficiency of the Optima 4.3 Multiple Cylinders 5 Conclusions References Flapping Foil Hydrokinetic Turbine: From a Strongly Coupled FSI Solver to the Experiment in a Confined Channel 1 Introduction 2 The Numerical Modeling 2.1 Main Features of the CFD Model 2.2 Fluid-Structure Coupling 2.3 Numerical Results 3 Fully-Passive Flapping Foil Prototype 3.1 Experimental Setup 3.2 Friction Characterisation 4 Conclusions and Perspectives References Machine Learning of Dynamics with Applications to Flow Control and Aerodynamic Optimization 1 Introduction 1.1 The Big Data and Small Data Limits 1.2 Combinatorially Large Optimizations 1.3 Parsimonious Models and Physics 2 Machine Learning for Flow Modeling and Discovery 2.1 Linear Models 2.2 Sparse and Parsimonious Models 2.3 Neural Networks 2.4 Other Emerging Approaches 3 Machine Learning for Optimization and Control 3.1 Optimization 3.2 Control References Compressibility Effects in Fluid-Structure Interaction Effect of Frozen Turbulence Assumption on the Local Blades Vibration on the Choke Flutter Instability in Transonic UHBR Fan 1 Introduction 2 Numerical Methods 2.1 Steady RANS Solver 2.2 Time-Linearised URANS Solver 2.3 Aeroelasticity 2.4 Frozen Turbulence Assumption 3 Studied Configuration 3.1 UHBR Fan 3.2 Steady Flow 3.3 Modeshape 4 Effect of Frozen Turbulence Assumption 4.1 Effect on the Total Damping Coefficient 4.2 Effect on Main Flutter Source 4.3 Effect on the Stability Induced by Pressure Side Zones 5 Conclusions References Numerical and Experimental Investigations of Buffet on a Diamond Airfoil Designed for Space Launcher Applications 1 Introduction 2 Methods 2.1 Experimental Setup 2.2 Numerical Setup 3 Analysis of Results 3.1 At Wind Tunnel Conditions 3.2 Influence of Reynolds and Mach Numbers 4 Fluid Structure Interaction: Impact of Buffeting on Aileron 5 Conclusion References Numerical Simulation and Modelling of a Morphing Supercritical Airfoil in a Transonic Flow at High Reynolds Numbers 1 Introduction 2 Description of the Numerical Experiment 2.1 Geometry in Use and Flow Parameters 2.2 Turbulence Modelling and Numerical Parameters 2.3 Numerical Method 3 Results 3.1 Force Coefficients Under the Buffet Effect 3.2 A Frequency Lock-In 4 Conclusions References Fluid-Structure Simulation of a Piston Shock-Tube Using an Adaptive ALE Scheme in the Non-ideal Compressible-Fluid Regime 1 Introduction 2 Methods 2.1 Adaptive GCL-Compliant Scheme 2.2 Thermodynamic Modeling 2.3 Computational Procedure 3 Results 4 Conclusions References Fluid-Structure Interaction, Morphing and Control Fabrication and Characterization of Folded Foils Supporting Streamwise Traveling Waves 1 Introduction 2 Fluid Mechanical Actuation Specifications 3 Construction 3.1 Composite Construction 3.2 Linear Motors 3.3 Assembly 4 Characterization 4.1 Force 4.2 Frequency 5 Conclusions References The Aerodynamic and Aeroacoustic Effect of Passive High Frequency Oscillating Trailing Edge Flaplets 1 Introduction 2 Experimental Set-Up 2.1 Velocity Field Measurements 2.2 Acoustic Measurements and Data Processing 3 Results and Discussion 3.1 Velocity Field Measurements 3.2 Aeroacoustics 4 Conclusion References Electroactive Morphing Vibrating Trailing Edge of a Cambered Wing: PIV, Turbulence Manipulation and Velocity Effects 1 Introduction 2 Prototype Design 3 Experimental Setup 4 Global Morphing effect—Force Measures 5 Flow dynamics—PIV 5.1 Streaklines 5.2 Proper Orthogonal Decomposition 6 Discussion 7 Conclusions References Camber Actuation of an Articulated Wing with Electromechanical Actuators 1 Introduction 2 Presentation of the Flap and Its Actuation 2.1 Flap Details 2.2 Actuation Choices 3 Electromechanical Actuator Description 3.1 Motor 3.2 Gearbox 3.3 Screw and Nut 3.4 Plays 4 Mechanical Integration and Control 4.1 Integration and Bearing Utility 4.2 Close Control Strategy 5 Conclusions References Numerical Study of Trailing-Edge Dynamics of a Two Element Airfoil-Flap with Morphing Flap at High Reynolds Number 1 Introduction 2 Numerical Method and Turbulence Modelling 2.1 Flow Configuration 2.2 Numerical Methods 2.3 Multiblock Grid 2.4 Results Validation 2.5 Turbulence Modelling 3 Static Configuration Versus Morphing 3.1 Wake Instabilities 3.2 Modal Analysis 3.3 Mean Fields in the Wake 4 Conclusions References The Passive Separation Control of an Airfoil Using Self-adaptive Hairy Flaps 1 Introduction 2 Numerical Method 2.1 Lattice Boltzmann Method 2.2 The Immersed Boundary Method 2.3 Model of Flexible Flap 3 Results and Discussion 3.1 Flow Over a NACA0012 Airfiol 3.2 Flow Over a NACA0012 Airfiol with a Rigid Fiap 3.3 Flow Over a NACA0012 Airfiol with a Flexible Fiap 4 Conclusions References Dynamic Response of Wall-Mounted Flaps in an Oscillating Crossflow 1 Introduction 2 Methods 2.1 Lattice Boltzmann Method 2.2 Finite Element Method 2.3 Immersed Boundary Method 2.4 Fluid-Structure Coupling 3 Simulation Setup 4 Results 4.1 Validation 4.2 Effect of Array Length 5 Conclusions References Effects of an Oscillating Flap on the Main Airfoil Unsteady Lift in Grid Turbulence 1 Introduction 2 Experimental Setup 3 Unsteady Lift Results for the Model Wing Without a Flap 4 Unsteady Lift with Flap in Steady Conditions 5 Unsteady Lift with Flap in Sinusoidal Forcing 6 Unsteady Lift with Flap in a Closed Loop Excitation 7 Conclusions References Fast Sensitivity Analysis for the Design of Morphing Airfoils at Different Frequency Regimes 1 Introduction 2 Numerical Setup and Primal Flow 3 Sensitivities for Quasi-Steady Morphing 4 Approximating Sensitivity for High Frequency Deformations 5 Conclusions References Thin Shear Layers in High-resolution Direct Numerical Simulations of Turbulence 1 Introduction 2 DNS Data of Turbulent Flows 3 Three Different Types of Thin Shear Layers 3.1 T/T 3.2 T/NT (of TBL) 3.3 T/W 4 Conclusions References Scaling Laws for an Airfoil with MFC-Actuated Trailing Edge Plate 1 Introduction 2 The Mathematical Model 3 Experimental Validation 4 Results and Discussion 5 Conclusions References CFD Simulations with Dynamic Morphing on the Airbus A320 Airfoil 1 Introduction 2 Flow Modeling 2.1 Solver 2.2 Deformation 2.3 Grid Generation 3 Computational Results 4 Discussion and Conclusion References URANS Flow Calculations Around a Morphing and Heaving Airfoil 1 Introduction 2 Method 2.1 Numerical Flow Solver 2.2 Conformal Mapping and Grid Generation 3 Results and Discussion 3.1 Steady State Calculations 3.2 Morphing Airfoil at 30 Hz 3.3 Morphing Airfoil at 300 Hz 3.4 Morphing and Heaving Airfoil at 50 Hz 3.5 Discussion 4 Conclusions References Bifurcations and Analytic Modelling in FSI General Boundary Identification Through Surface Pressure Measurements on a 2-D Foil 1 Introduction 2 Experimental Methods 2.1 Simulation Model Definition 2.2 Estimation Algorithm Definition 2.3 Estimation Algorithm Implementation 3 Results and Discussion 3.1 Standard Estimation Method 3.2 Weighted Estimation Method 3.3 Multiple Shapes 3.4 Error Discussion 4 Conclusion References Analytic Modeling of a Size-Changing Swimmer 1 Introduction 2 Methodology 2.1 Coupled Swimming Model 2.2 Translation Model 2.3 Deformation Model 2.4 Jetting Escape Model Validation 3 Pulsed Swimming Results 4 Conclusions References Author Index