Vortex Shedding in Bridge Engineering

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Vortex Shedding in Bridge Engineering. Kessock Bridge Case Study. Outline. Introduction of Bridge Aeroelasticity Research Methodology Kessock Bridge Background Experimentation Computational Simulation (CFD). Introduction. Bridge Failures in the History (wind-induced instabilities) - PowerPoint PPT Presentation

Text of Vortex Shedding in Bridge Engineering

  • Vortex Shedding in Bridge EngineeringKessock Bridge Case Study

  • OutlineIntroduction of Bridge AeroelasticityResearch MethodologyKessock Bridge BackgroundExperimentationComputational Simulation (CFD)

  • IntroductionBridge Failures in the History (wind-induced instabilities)Menai Strait Bridge; Bright Chain Pier; Tay Bridge (UK)Deer Isle Bridge; Golden Gate Bridge (US)Tacoma Narrows Bridge (Benchmark)Classical Flutter Theory (Theodorsen)Flight Failures (wing and wing-aileron flutter)Langleys Aerodome/monoplane flight failureFokker D-8 wing failures (1st world war)

  • Bridge AeroelasticityFlutter Theories by R.H.Scanlan;Buffeting Theories by A.G.Davenport;Vortex Induced Oscillation (VIO) Lock-in Phenomenon;Galloping;Static Divergence;Aim of ProjectUnderstanding the Physics of Vortex Induced Oscillation & Lock-in in Bridge Aeroelasticity

  • Research MethodologyAvailable Research TechniquesAnalytical MethodExperimental MethodComputational Simulation (CFD)MethodologyComparison of Experimental and CFD Results;Parametric Study via CFD;

  • Kessock Bridge BackgroundLocated in Inverness Scotland;Encounters Relatively Strong Wind due to Local TopologyCentral Span 240m;Inverted U-shape Deck Cross-section Aerodynamically and Aeroelastically Unstable;Full Scale Measurement (10.1991-05.1992 by Owen et.al)Wind Tunnel Test (Dec.2003 UoN in UK & NTU in Sg)CFD Computational Simulation (in progress)

  • ExperimentationWind Tunnel TestCollaborative Experiment University of Nottingham and NangYang Technological University1:40 Scale Sectional Model of Kessock BridgeForce Coefficients vs. Angles of AttackComprehensive Full Scale DataVerification of Experimental Data

  • Computational Fluid Dynamics (CFD)Based on Navier-Stokes Equation;Spatial and Temporal Discretisation;Turbulence Modelling :-Reynolds-Averaged Navier-Stokes (RANS)Detached Eddy Simulation (DES)Large-Eddy Simulation (LES)Direct Numerical Simulation (DNS)

  • CFD Simulation1/40 Sectional Model Wind Tunnel ModelSST and DES Turbulence SchemeFine Hexahedral Mesh (0.8m-3.7m cells)O-Grid Construction Non-conformal General Grid Interface (GGI)

  • Mesh Independence TestSST ModelAngles of Attack - 10 (2 increment);Lift and Drag Coefficients;Hexahedral Meshes :-0.8m, 1.3m and 3.7m cells;Different Arrangement of Cell Structure;DES for Parametric Study

  • Parametric StudyDES Run :-Finer Mesh;Wind Speed and Direction Effects;Varying Turbulence Intensity;Fluid Structure Interaction;Implication of Computation Facility :-Accuracy of Simulation;Realisticity of Simulation;

    Intro of research projectKB background, inc. the topological information & data structure;

    Commonly known phenomena in the context of bridge aeroelasticity 4 or 5Insofar as structural fatigue issues are concerned, VIO plays a vital role; especially when lock-in initiates, could cause failure of structureMethodology (integrating original intermediate objectives)After studying available research techniques, mainly categorized as analytical approaches, experiments and computational simulation and evaluating potential and limitation of each; it has been recognized that CS, with appropriate application, has great advantages in wind engineering, espeically considering its facilitating easy manipulation of inputting parameters and constantly varying assumptions in any researches; while experiments give insights as to what would happen realistically in the physical world, thus good for validation tool;Linking back to the aim, hopefully insightful outputs to help better understanding of VIO in BA;Analytical MethodSimplification and Assumption;More Validation and Development;Experimental MethodDisturbances in Testing Environments;Instrumentation Biases & Erroneous Data;Time-consuming and Expensive;Computational Simulation (CFD)Requirement of Computer Power;Judgement of Realisticity of Simulation;

    Show KB location map & then set as background with 50% transparencyCollaborative Experiment between University of Nottingham and NangYang Technological University in SG;1:40 Scale Sectional Model of Kessock Bridge (1.5*0.5m with details);Sectional model identical to that in the wind tunnel testDES model & later on LESFine Hexa mesh with good BL construction;Sufficient time step for statistically converged resultsInsert plots before 2nd bullet, not conclusive as which mesh is the best, both mesh size and arrangement of cells hence another proposal;