Flow-induced vibrations of a rotating cylinder in an arbitrary direction

摘要

The flow-induced vibrations of an elastically mounted circular cylinder, free to oscillate in an arbitrary direction and forced to rotate about its axis, are examined via two- and three-dimensional simulations, at a Reynolds number equal to 100, based on the body diameter and inflow velocity. The behaviour of the flow–structure system is investigated over the entire range of vibration directions, defined by the angle $unicode[STIX]{x1D703}$ between the direction of the current and the direction of motion, a wide range of values of the reduced velocity $U^{star }$ (inverse of the oscillator natural frequency) and three values of the rotation rate (ratio between the cylinder surface and inflow velocities), $unicode[STIX]{x1D6FC}in {0,1,3}$ , in order to cover the reference non-rotating cylinder case, as well as typical slow and fast rotation cases. The oscillations of the non-rotating cylinder ( $unicode[STIX]{x1D6FC}=0$ ) develop under wake-body synchronization or lock-in, and their amplitude exhibits a bell-shaped evolution, typical of vortex-induced vibrations (VIV), as a function of $U^{star }$ . When $unicode[STIX]{x1D703}$ is increased from $0^{circ }$ to $90^{circ }$ (or decreased from $180^{circ }$ to $90^{circ }$ ), the bell-shaped curve tends to monotonically increase in width and magnitude. For all angles, the flow past the non-rotating body is two-dimensional with formation of two counter-rotating spanwise vortices per cycle. The behaviour of the system remains globally the same for $unicode[STIX]{x1D6FC}=1$ . The principal effects of the slow rotation are a slight amplification of the VIV-l