Surface roughness effect on cylinder vortex-induced vibration at moderate Re regimes. (15th March 2021)

• Record Type: Journal Article
• Authors: Han, Xiangxi; Tang, Youhong; Meng, Zhanbin; Fu, Fei; Qiu, Ang; Gu, Jian; Wu, Jiaming
• Is Part Of: Ocean engineering. Volume 224(2021)
• Publication Date: 2021-03-15
• Subjects: Fluid-structure interaction -- Vortex-induced vibration -- Marine riser -- Numerical simulation -- Surface roughness; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2021.108690
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: The marine riser is the key equipment connecting the floating platform with the seabed wellhead, and the vortex-induced vibration (VIV) is the main cause of its fatigue damage, which contains complex and substantial dynamics content. Marine risers are operated for a long time. As time goes by, marine organisms will attach on the marine riser surfaces, thus significantly affect their surface roughness of the riser. The increased surface roughness makes the dynamic characteristics of the riser VIV more abundant and complex, including jumping, multi-frequency vibration, broadband vibration, resonance and other dynamic contents. In this study, based on the bidirectional fluid-structure coupling method of computational fluid dynamics (CFD) and computational structure dynamics (CSD), the modified model of rough wall velocity gradient is introduced, and the calculation program of a rough cylinder wall velocity gradient is compiled and embedded into the numerical calculation program of a smooth cylinder VIV to construct the numerical calculation program of a rough cylinder VIV. The program is used to study effects of various key parameters, including surface roughness, and inflow velocities, on the vibration response characteristics, dynamic characteristics, wake vortex shedding patterns and vibration trajectories of a rough cylinder. The differences of VIV characteristics are systematically studied to reveal the nonlinear dynamic behavior of a rough cylinder VIV, such as jumping, multi-frequency vibration, resonance, etc. The influence mechanism of surface roughness on a cylinder VIV is explored to provide a scientific theoretical basis and a practical engineering method for vibration control of a rough marine riser. Highlights: The law of the wall modified for roughness is introduced to construct the numerical program of a rough cylinder VIV. The program is used to study effects of various key parameters on the rough cylinder VIV characteristics. The differences of VIV characteristics between smooth cylinder and rough cylinder are systematically. The surface roughness of the cylinder will inhibit the formation of 2T wake vortex shedding pattern.