Modeling VIV Supression Using Negative Lift Coefficients

Vortex-Induced Vibration (VIV) is a complex, non-linear fluid-structure interaction problem with important consequences for offshore risers, tendons and other tubulars. The prevalent approach in the industry is to use semi-empirical formulations to estimate VIV amplitudes, frequencies and the resulting fatigue damage. These semi-empirical techniques estimate VIV response amplitude by considering the balance of power input into the pipe due to vortex-shedding and the loss of power from the pipe due to damping. At the heart of this method are lift coefficient curves, which are used to estimate power input into the pipe. A key difficulty of this method is modeling the response of pipes with mitigation devices (strakes and fairings). This paper discusses the use of negative lift coefficient curves for estimating VIV response from mitigation devices. The author’s show how damping is handled in Shear7 using this approach. Results of comparisons between predicted and measured data show that negative lift curves are an effective means of modeling damping from VIV mitigation devices.