Modification of a Square Cylinder Wake through a Secondary Upstream Cylinder

Abstract

Abstract One of the inherent characteristics of a bluff body is the large drag coefficient even at a relatively low velocity. The condition is made worse when the flow separates from the body, and a time-dependent flow occurs downstream of the body; i.e. a vortex shedding phenomenon. It has been shown that suppression of the vortex shedding can significantly reduce drag coefficient of the bluff body. The present study investigates the intensity of the resulting laminar wake of a single and two square cylinders in tandem arrangement, where the intensity was measured through the lift force signals. The findings indicated that the presence of the secondary cylinder significantly altered the magnitude of lift force of the cylinder system, particularly at high Reynolds numbers under the laminar flow regime. Furthermore, the magnitude of lift force was lower when the secondary cylinder was separated from the main cylinder as compared to the case where both cylinders were attached.