The numerical study of two-degree-of-freedom vortex-induced vibration of the downstream cylinder in tandem arrangement
串列双圆柱绕流下游圆柱两自由度涡致振动研究

A numerical study has been conducted into two-degree-of-freedom vortex-induced vibrations of the downstream elastic circular cylinder in tandem arrangement. The results show that (i) the peak value of the displacement of the cylinder for two-degree-of-freedom is larger than that for one-degree-of-freedom as well as the ratio of the frequency for which this maximum occurs; (ii) the lift of the cylinder in a wake is more larger than that in a uniform flow, but the drag behaves contrary; (iii) the response of the displacement of the downstream cylinder is less of "sensitivity" than that of the cylinder in a uniform flow at various natural frequency of the cylinder; (iv) the "beating", that is the response of the oscillating cylinder involves various frequencies, are clearly showed in a wake at various ratio of the frequency from 1.16 to 0.87 but not in the uniform flow. The ALE method is adopted with an H-O type of non-stagger grid incorporating the DDM (domain decomposition method). The N-S equation's convection term and dissipation term are discretized using the third-order upwind compact scheme and the fourth-order central compact scheme, respectively. The motion of the cylinder is modeled by a spring-damper-mass system and solved using the Runge-Kutta method. By simulating the non-linear interaction of the fluid-structure system, we successfully captured the "beating" and "phase switch" phenomena.