Vortex-induced rotational vibration of an eccentric circular cylinder at low Reynolds number of 100

Vortex-induced rotational vibration (VIRV) of an eccentric circular cylinder in uniform flow is studied by fluid-structure interaction (FSI) simulation. Firstly, the mechanics model of VIRV of an eccentric circular cylinder in laminar flow is proposed, and the corresponding mathematical formulations are derived. Then, an FSI solver combining the modified characteristic-based split finite element method, dual-time stepping method and spring analogy method is developed for VIRV of a bluff body in laminar flow, and its stability and accuracy are validated by two benchmark FSI problems. Using FSI code validated, VIRVs of an eccentric circular cylinder at Re = 100, & zeta; (damping ratio) = 0, m*(mass ratio) = 2, 5 and 10, l/D (l is the eccentricity and D is the cylinder diameter) = 0-5, and Ur (reduced velocity) = 1-30 are computed. The effects of m*, l/D and Ur on the dynamic response, fluid load and vortex pattern of the eccentric cylinder are analyzed. Significant rotational response with maximum angle up to 36.3 & DEG; is observed, and some VIRV features such as "lock-in" are analyzed. Finally, the underlying mechanisms of VIRV characteristics of the eccentric cylinder are discussed based on the governing equation of vibration. The model proposed could be taken as a benchmark for VIRV of the bluff body in laminar flow, and the results obtained are insightful to the design of VIRV-based energy harvesters.