Velocity characteristics in the wake of an oscillating cylinder

Abstract

This thesis describes the results of over 2000 experimental runs conduced at the MIT Ship Model Testing Tank. A rake of constant temperature anemometers is employed to study the spanwise velocity correlation and the vertical velocity profile downstream of a vibrating cylinder. Experiments involve either free vibration implemented through a force feedback system or forced sinusoidal motion. All experiments are conducted at a towing speed within the subcritical flow regime at Re ~ 3 x 104. This thesis explores the connection between these downstream velocity properties and the vortex-induced vibrations of the cylinder. In addition to downstream velocities, experimental data include lift and drag forces and cylinder displacement. Vortices are found to be correlated along the entire length of the test cylinder only within a specific band of motion amplitudes and frequencies. Overall, forced oscillations produce vortices that are more organized and well correlated than those shed from a freely vibrating cylinder.