Flow about cylinders with surface perturbations

Abstract

An experimental study of circular cylinders with equally spaced two-dimensional surface perturbations in a uniform flow at Reynolds number of 3 × 104 and very low free-stream turbulence is presented. The investigation concentrates on how the major flow characteristics are influenced by the geometry of the perturbations, their distribution and spacing, and orientation relative to the uniform flow. Measurements of body-surface pressures, vortex-formation length, spacing between the shear layers, vortex-shedding frequency and mean and fluctuating velocities within the wake as well as the drag force are presented. It is found that the drag coefficient and Strouhal number vary significantly with the location of the perturbations. The influence of the surface perturbations on the major flow characteristics are described and correlated with the near-body flow field. © 1997 Academic Press Limited.