Vortex-induced vibrations of an elastic circular cylinder

A numerical study of a uniform how past an elastic circular cylinder using the discrete vortex method incorporating the vortex-in-cell (VIC) technique has been undertaken. The Reynolds number is kept at 200 for all calculatio ns and the cylinder motion is modelled by a spring-damper-mass system. The fluid motion and the structural responses are solved in an iterative way so that the interactions between the fluid and the structure can be accounted for properly. Analyses of the cylinder responses, the damping, the induced forces, the vortex shedding frequency and the vortex structure in the wake have been carried out. The results show that fluid damping is responsible for a limit-cycle oscillation behaviour even when the system natural freque ncy is close to the vortex-shedding frequency. Reasonable agreement with pr evious experimental data and computational results is obtained in the compa rison of the amplitude of the limit-cycle oscillations. The results further show that the cylinder oscillations could be as large as 0.57 diameter und er certain flow conditions and structural properties. Finally, it is shown that a one-degree-of-freedom structural model yields results that are only in qualitative agreement with a two-degree-of-freedom model. In other words , the streamwise oscillations also have a substantial effect on the transve rse vibrations and their characteristics. (C) 1999 Academic Press.