Visualization of the flow above the free end of a finite cylinder

Abstract

Flow over surface-mounted circular cylinders of finite height, with aspect ratios AR = 3 and 7 (AR = H/D, where H and D are the cylinder’s height and diameter, respectively), at a Reynolds number Re = 4.2 × 104, has been investigated using the snapshot proper orthogonal decomposition (POD) method and the swirling strength criterion. The instantaneous velocity fields in two spanwise elevations above the cylinder’s free end, at z/D = 0.016 and 0.08, were generated by a two-component particle image velocimetry (PIV) system. Of interest was to identify turbulent flow structures of different scales within the free-end flow field, and investigate how the AR affects these structures.