On reducing lift and drag forces of a stationary circular cylinder using side-by-side pair of inward rotating cylinders

Abstract

Effect of side-by-side pair of inwardly rotating circular cylinders on the nature of drag and lift forces of the stationary circular cylinder is numerically investigated for Reynolds number Re = 100. Non-dimensional rotation rates of cylinders in consideration are α = 0, 1, 3, and 5. Center to center gap spacing between rotating cylinders is taken as 6D (D is cylinder diameter), and the stationary cylinder is centrally placed in the gap. For the case of two side-by-side inward rotating cylinders, above a certain critical rotation rate, Chan et al. [1] reported the formation of a virtually elliptical body accompanied by vortex suppression. Drag on both the cylinders became almost zero after the formation of a virtually elliptical body. The present study aims to use the same concept of a virtually elliptical body to reduce the drag and lift forces on a stationary circular cylinder. At α = 3, complete suppression of vorticity is observed, followed by the formation of a virtual elliptical body at α = 5. With an increase in α from 0 onwards, the drag coefficient for the stationary cylinder reduces and becomes zero at α = 5.