Vortex-induced vibration response of the cylinder inspired by Terebridae

Vortex-induced Vibration (VIV) responses of the three-dimensional cylinders inspired by Terebridae are numerically investigated at the Reynolds number ranges of 0.8 x 10(4) <= Re <= 8.0 x 10(4). By Terebridae, we mean that inspired by its slender structural shape, and whether it can be used to improve the VIV suppression performance of the traditional structures. Three different cylinders are considered, including the smooth cylinder (T-0), the Terebridae-inspired cylinder with four-start helical ribs (T-1), and the Terebridae-inspired cylinder with six-start helical ribs (T-2). The VIV responses of T-1 and T-2 is effectively suppressed, and T-1 shows better suppression performance. The results show that the maximum cross-flow amplitude ratio of T-1 is reduced by 70.7 % compared with that of T-0, and the maximum in-line amplitude ratio of T-1 is reduced by 85.7 % compared with that of T-0. Compared with the maximum mean-drag coefficient of T-0, it is reduced by 44.0 % for T-1. In the high Reynolds number ranges, the galloping phenomenon does not occur for T-1 and T-2, and the relationship between the mean-drag coefficients of T-0, T-1 and T-2 is C-d (T-2) > C-d (T-1) > C-d (T-0). It is found that the changes of Q-criterion vortex structure and wake flow play an important role in the VIV response. The Q-criterion vortex of T-0 is a slightly curved linear shaped, and the Q-criterion vortices of T-1 and T-2 are break up. The three-dimensional geometry of the Terebridae-inspired cylinder undermines the correlation of vortex-shedding along the span. The wake flow of T-0 can develop normally. The wake flow of T-1 quickly rolls up after passing through the top separation point, and the reattachment of the wake vortex destroys the development of the original wake flow. The continuous development of the boundary layer is destroyed by multiple Terebridae-inspired ribs of T-2, resulting in the broken wake. Through the comparison of vortex force, it can be seen that the vortex force of T1 is significantly weakened compared to that of T-0, and this also indicates that the three-dimensional geometry of T-1 can effectively reduce the intensity of the wake flow.