Numerical investigation on VIV suppression of the cylinder with the bionic surface inspired by giant cactus

Vortex-induced vibration (VIV) responses of the cylinders with the bionic surfaces inspired by giant cactus are numerically studied, and the range of Reynolds number is 8.0 × 10³ < Re < 5.6 × 10⁴. The dynamic response of the structure adopts Newmark-beta method. The effects of the height ratios (K_s/D, K_s is the height of the bionic structure) on VIV suppression are discussed in detail, and five different height ratios (K_s/D) include T1 (K_s/D = 0.000), T2 (K_s/D = 0.025), T3 (K_s/D = 0.050), T4 (K_s/D = 0.075) and T5 (K_s/D = 0.100). The VIV response process is characterized by four sub-regions (Region I, Region II, Region III and Region IV). As the height ratios of the bionic structures increase, the range of the large-amplitude-motion region gradually decreases, and the lock-in range is smaller. The maximum amplitude ratio in cross-flow direction decreases from 1.50 (T1) to 0.75 (T5), and it reduces by about 50%. The maximum in-line amplitude ratio decreases from 0.35 (T1) to 0.12 (T5), which reduces by about 65.7%. For T1 and T2, the jump phenomenon of frequency ratio occurs between region II and region III. However, the jump phenomenon of frequency ratio occurs between region I and region II for T3, T4 and T5. The maximum mean-drag-coefficient decreases from 3.00 (T1) to 2.25 (T5), and it reduces by about 25%.