Simultaneous CFD evaluation of VIV suppression using smaller control cylinders Hongjun Zhu n , Jie Yao, Yue Ma, Hongnan Zhao, Youbo Tang State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China article info Article history: Received 21 September 2014 Accepted 27 May 2015 Available online 25 June 2015 Keywords: VIV suppression Control cylinder Vortex shedding FSI CFD abstract Two-degree-of-freedom vortex-induced vibrations (VIV) of a circular cylinder with and without two smaller control cylinders are investigated numerically by computational fluid dynamics (CFD) models coupling with a fluid–structure interaction (FSI) computational method. The numerical model is validated against experimental data of VIV of an isolated cylinder in uniform current. The study is aimed to investigate the effect of smaller control cylinders on VIV suppression. The trajectories of cylinder motion, amplitude response, and temporal evolution of vortex shedding and streamlines are obtained by conducting a series of simulations. And the effect of Reynolds number, located angle and rotational rate of small control cylinders are discussed in detail. It is found that placing small cylinders at 451 to the downstream vector can achieve a good suppression effect, but the effect is different at different Re. Rotating control cylinders with a reasonable rotation velocity can further enhance the VIV suppression by injecting enough momentum into the boundary layer of the main cylinder. The best effect is found at U c ¼10, which has a 64.56% reduction in the transverse vibration response. & 2015 Elsevier Ltd. All rights reserved. 1. Introduction Flow over a circular cylinder is common occurrence in many branches of engineering such as civil, mechanical and ocean engineering, for example flows past riser tubes or heat exchangers, and wind blowing past bridge cables or chimneys. Therefore, flow wakes of cylinder have been extensively studied by employing theoretical, numerical and experimental means since 1900. It is shown in the reviews by Berger and Wille (1972), King (1977), Sarpkaya (1979, 2004), Bearman (1984, 2011), Naudascher and Rockwell (1993), Sumer and Fredsoe (1997), Gabbai and Benaroya (2005), Williamson and Govardhan (2004, 2008), and Wu et al. (2012). Vortex shedding presents in the wake when Reynolds number exceeds a critical value (Re ¼ 100), which causes a significant pressure drop on the rear surface of cylinder and induces structural vibration (vortex-induced vibration, VIV). Vortex shedding frequency being in the vicinity of structural frequency may lead to high amplitude oscillations, which causes severe damage and fatigue failure. Therefore, the effective control of vortex shedding is important in engineering applications. Especially in offshore industry, catastrophic environmental and enormous economic consequences may be incurred as a result of failure of risers, spars or some other similar structures. In the past 30 years, many investigations have been conducted on the VIV suppression. The review articles by Gad-el-Hak and Bushnell (1991, 2000), and Choi et al. (2008) have discussed the control Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jfs Journal of Fluids and Structures http://dx.doi.org/10.1016/j.jfluidstructs.2015.05.011 0889-9746/& 2015 Elsevier Ltd. All rights reserved. n Corresponding author. Tel.: þ86 28 83032206. E-mail address: ticky863@126.com (H. Zhu). Journal of Fluids and Structures 57 (2015) 66–80