Three distinct response regimes for the transverse Vortex-Induced Vibrations of circular cylinders at low Reynolds numbers

The paper reports and discusses the results of a numerical investigation of the low-Reynolds-number transverse Vortex-Induced Vibrations (VIV) of low-mass-ratio elastically supported circular cylinders. Simulations were conducted over a large range of reduced velocities, from 2.52.5 to 20.020.0, at Reynolds numbers from 50 to 400. The objective of the study was to ascertain the dependency of the transverse vibrational behaviour of low-mass-ratio circular cylinders on their mass ratio. Simulations were conducted at mass ratios representative of a cylinder in water: 1, 2, 5 and 10, and for reference to higher mass ratio VIV at a mass ratio of 50. It was found that, at low Reynolds numbers, Re⩽400Re⩽400, transversely vibrating circular cylinders exhibit three distinct regions of response: a primary response which occurs at and around resonance and is that normally associated with VIV, secondary or super-harmonically excited responses, and a tertiary, or infinite lock-in, response. The paper reports and discusses the response and vortex shedding characteristics of these three response regimes.