Flow around a square cylinder with a detached downstream flat plate at a low Reynolds number

Abstract

This paper investigates the interaction of a square cylinder wake with a detached flat plate of length equal to one cylinder height (D) at various downstream locations (G). Two modes of wake-plate interaction are observed from this study. For short gaps (G ≲ 2D), a shear layer-plate interaction is observed, where the first flow regime is generated. In this regime, the shear layers roll up downstream of the plate. The optimal location of the plate is found at G ≲ 2D for maximum reductions in fundamental vortex shedding frequency, root mean square lift and mean drag of the cylinder. A sudden jump in Strouhal number is observed between 2D ≲ G ≲ 2:5D, which suggests a transition into a new mode of wake-plate interaction. For long gaps (2:5D ≲ G ≲ 5D), a vortex-plate interaction is observed, where the second flow regime is generated. In this regime, the shear layers roll up within the gap, and the flow structure at near to the cylinder is almost unchanged with the gap.