Effect of Hole-uniformity of Shrouds on Vortex Shedding Suppression behind a Circular Cylinder

Abstract

A passive flow control method over a circular cylinder using perforated shrouds was computationally investigated to manipulate the unsteady wake behind the circular cylinder for vortex shedding suppression. The perforated shrouds were of 33% porosity with uniform and non-uniform holes. The computation was performed at low Reynolds number (based on the circular cylinder diameter), Re = 300. The objective of the study is to examine the effect of hole-uniformity of the perforated cylinders on the vortex shedding behind the circular cylinder. It was found that both perforated shrouds (uniform and non-uniform holes) significantly suppressed the vortex shedding behind the cylinder, although with an increased drag due to normalization according to cylinder diameter. The perforated shrouded cylinder with non-uniform holes has longer vortex formation length, suppressing vortex better than that of the uniform holes distribution. The intensity of vortices behind the shrouded cylinder wake with non-uniform holes was also considerably smaller than that of the uniform holes.