Numerical simulation of VIV for an elastic cylinder mounted on the spring supports with low mass-ratio

Abstract

With the development of the offshore deep water oil industry many researchers are focusing on the vortex-induced vibrations (VIV) of deep risers. In the present work, Reynolds-averaged Navier-Stokes (RANS) equations were combined with the SST κ−θ turbulent model to simulate the stream-wise and transverse motion of an elastically mounted cylinder with a low mass-ratio, a natural frequency ratio of f _x /f _y = 1 and an Re number between 5 300 and 32 000. The four-order Runge-Kutta method was applied to solve the oscillating equation of the cylinder. The relationship between reduced velocity and parameters of the cylinder, including the lift coefficient, the drag coefficient, displacement and the vortex structure were then compared with recent experimental results and discussed in detail. The present numerical simulation reproduced effects have been observed in experiments, such as the lock-in phenomenon, the hysteretic phenomenon and beating behavior.

摘 要

近年来, 随着深海石油工业的发展, 立管的涡激振动现象越来越受学者们关注. 使用RANS 方程求解器, 并结合SST κ−θ 湍流模型, 对横向和流向自然频率比为1的低质量比弹性支撑圆柱体的两自由度运动进行了数值模拟, 计算雷诺数范围为5 300 至32 000. 采用四阶Runge-Kutta 方法求解柱体的振动方程. 并结合近期物理实验结果对升力系数、 阻力系数、 位移和尾涡模式进行了详细比较和讨论. 较好地再现了试验观察到的锁定、 迟滞、 差拍等现象.