Three-dimensional Numerical Simulations and Proper Orthogonal Decomposition Analysis of Flow Around a Flexibly Supported Circular Cylinder
Master thesis
Permanent lenke
https://hdl.handle.net/11250/2786191Utgivelsesdato
2021Metadata
Vis full innførselSamlinger
Sammendrag
Numerical simulations of turbulent flow around stationary and vibrating cylinders at Re = 3900 areperformed using the Large Eddy Simulation (LES) approach. Detailed convergence and validationstudies confirm feasibility of the present model to accurately predict the Vortex-Induced Vibrations(VIV) and turbulent wake characteristics. The thesis is divided into seven chapters. First a briefintroduction to the topic is given. Chapter 2 gives a brief review of the theory for flow around circularcylinders. In chapter 3 the theory of Computational Fluid Dynamics (CFD) is given. In chapter 4 a seriesof simulations for a stationary cylinder configuration with different mesh and time step parameters areperformed to find an optimal balance between the computational cost and accuracy. Furthermore,simulation results are compared with an extensive dataset from multiple experimental studies showinga very good agreement of the present simulation results with the experimental data. In chapter 5simulations of a self-excited cylinder vibrating in the cross-flow direction are performed at threedifferent values of reduced velocity. The flow fields are analyzed and different vortex shedding modesare categorized and then compared with the vortex shedding map derived from forced oscillation tests.Proper Orthogonal Decomposition (POD) is performed on sampled data in the wake of the cylinder toanalyze the turbulent flow. The present numerical model is found to give accurate predictions withrespect to essential parameters affecting the fluid-structure interaction of circular cylinder in thesubcritical regime. In chapter 6 a conclusion of the results is presented and chapter 7 presentsrecommendation for future work.