Flow-induced vibration of a flexible splitter-plate in the wake of a stationary cylinder

Abstract

The present work is on free-stream flow across a circular cylinder, with a detached flexible-plate. Using a levelset function-based immersed interface method, the effect of Reynolds number Re(75−150), non-dimensional gap G*(0.5−3.5) between the two structures and non-dimensional length L*(0.5−3) of the plate—with constant structural properties and thickness—is numerically studied. The effect of these parameters on the vibration characteristics of the plate along with the accompanying flow structures and engineering parameters are presented. The study demonstrates a correlation between the plate dynamics and the two flow-phenomenon: vortex-formation mode and vortex-interaction mode. Vortex-formation relates to the position of the leading and the trailing edge of the plate relative to the recirculation region behind the cylinder and is classified into three-regimes: pre-vortex formation regime-a, pre-vortex formation regime-b, and post-vortex formation regime, corresponding to smaller, intermediate, and larger plate-amplitudes, respectively. The vortex-interaction mode refers to the nature of interaction between the cylinder and the plate vortices and is classified into two-modes: constructive and destructive interactions, corresponding to larger and smaller amplitudes, respectively. The study shows that the plate oscillates with very large amplitude at larger Re, intermediate G*, and with plate length equal to the cylinder diameter. The flexible plate leads to a large suppression in the hydrodynamic forces and the vortex shedding frequency of the cylinder in the pre-vortex formation regime, with complete suppression in the vortex-shedding for larger plate-length L* at intermediate gap G*. Thus, the present system can be utilized as a plate-based energy harvesting device as well as a vortex-shedding control device.