A novel drag reduction and vortex shedding mitigation measure for a circular cylinder in the subcritical regime

Abstract

A novel aerodynamic measure, an arch mounted leeward of a circular cylinder, is proposed to reduce drag and mitigate vortex shedding for a circular cylinder. To confirm the validity of the proposed measure, the aerodynamic forces were measured through a force meter at the end of a cylinder, the wind pressure was measured at seven cross-sections of the cylinder, and elastically mounted cylinders were also tested. The results show that the arch significantly reduces drag and fluctuating lift by mitigating the vortex shedding in the subcritical Reynolds number range when the proper central angle is selected for the arch. The arch creates a higher base pressure at the leeward side and induces a pressure exchange and spanwise axial flow. This influence is extended along the length of the cylinder by the axial flow due to the strong correlation in the wake in the subcritical regime. Therefore, the arch lowers the base pressure and disrupts the formation of vortex shedding.