Numerical investigation on vortex-induced vibration of bluff bodies with different rear edges

Abstract

Vortex-induced vibration (VIV) responses of bluff bodies with different rear edges (semicircle (T1), triangular (T2), trapezoidal (T3) and rectangular (T4)) are numerically investigated using Computational Fluid Dynamics (CFD) methods for Reynolds number range of 8.0 × 103 < Re < 5.6 × 104. The two-dimensional unsteady Reynolds-Averaged-Navier-Stokes (RANS) equations and shear stress transport (SST) k-ω turbulence model are used to calculate the flow around bluff body. The Newmark-beta method is employed for evaluating the structure dynamics of bluff body. The effects of different rear edges on VIV responses are discussed in detail. The results show that the VIV response region can be divided into four regions (Region I, Region II, Region III and Region IV). The geometry of the bluff body's rear side can considerably affect VIV responses and vortex patterns. The amplitude responses of T2, T3 and T4 are suppressed compared with that of T1. When the rear edge is rectangular, the amplitude responses can be suppressed effectively and the vortex pattern is still 2S mode in the entire VIV response region, but the mean drag coefficient increases. The range of lock-in region is smaller for T2 and T4 compared with that of T1. The range of lock-in region is similar for T1 and T3. The motion trajectory of the typical figure “8” is observed.