A study of the effect of aspect ratio on vortex shedding behind circular cylinders

Abstract

The vortex shedding mode of circular cylinders at several aspect ratios is examined via spanwise flow visualization and hot-wire anemometry. For aspect ratios greater than 60 the shedding mode and shedding frequency results of previous investigators are compared with present results on cylinders with and without end modifications. For aspect ratios less than 60 the effects of rectangular endplates on vortex shedding are examined. The results reveal that nearly parallel shedding is generated in the wake of cylinders with appropriate endplates. The characteristics of this shedding are reported and a model is proposed to account for the production of nearly parallel shedding by the proximity of endplates.