A numerical study of vortex shedding from a circular cylinder vibrating in the in-line direction

Abstract

Purpose – The purpose of this paper is to investigate the influence of forced, in-line oscillation of a circular cylinder on an incoming incompressible flow field at different Reynolds numbers. Design/methodology/approach – A space-time finite element approach is employed to model the flow around an oscillating cylinder. Findings – The results show that two (2S), four (2P, two pair) and three vortices (P+S, one pair and one single) are shed in each cycle. In addition, a 2P o mode is also observed, which is similar to the 2P mode but the vortices of the 2P o mode differ in strength. The 2P mode of vortex shedding is observed along the entire wake of the flow field and 2P o mode in the far wake. In some cases, the vortex street is transformed as it travels towards the exit to produce new patterns. One such pattern is observed for the first time in the present work, which is referred to as 2P o * mode. The drag and lift coefficients observed are perfectly periodic at a Reynolds number of 200 and they reach a chaotic pattern as the Reynolds number is increased to a value of 350. Originality/value – Originality of the paper lies in the observation of 2P vortex shedding mode or its variants in the downstream of the cylinder.