Session: 08-03-01 Fundamental Vortex Induced Vibrations & Cylinder Hydrodynamics

Submission Number: 181917

Hysteresis in Inline Vortex-Induced Vibrations of a Circular Cylinder at a Subcritical Reynolds Number 

Vortex-induced vibrations (VIV) of cylindrical structures attract considerable attention due to their impact on fatigue damage of engineered structures and the rich fluid mechanics they involve. Although previous research has been largely focused on crossflow VIV— owing to its larger oscillation amplitudes — the investigation of inline VIV remains limited despite its significance. The pure inline VIV can serve as a first-order approximation for the complex multi-degree-of-freedom VIV system. While hysteretic transitions in VIV responses have been documented in scenarios such as pure crossflow and two-degree-of-freedom VIV, such phenomena have not been demonstrated for pure inline VIV.

In this study, we perform three-dimensional direct numerical simulations to examine the hysteresis behaviours of a low-mass-ratio cylinder undergoing pure inline VIV. The Reynolds number is fixed at 1000, and the reduced velocity (U*) is varied by adjusting the cylinder's natural frequency in water. We investigate hysteresis phenomenon by comparing the VIV responses obtained under zero initial conditions (ICs) with those from non-zero ICs, achieved by continuously increasing and then decreasing U*. The amplitude responses under zero ICs can be generally categorised into three lock-on branches: the primary branch (U* > 2.5), secondary branch (U* < 2.2) and desynchronised branch (2.2 < U* < 2.5). Significant hysteretic transitions are observed at non-zero ICs, resulting in distinct formations of hysteresis loops appearing in the vicinity of lock-on branch boundaries. Variations in the cylinder's response, force and wake characteristics, frequency and phase relationships between force and cylinder displacement will be interpreted in detail in the main text , accompanied by explanations of the underlying physical mechanisms.

Presenting Author: Chengjiao Ren South China University of Technology

Presenting Author Biography: Chengjiao Ren is an Associate Professor in School of Marine Science and Engineering, South China University of Technology. Dr. Ren received her Bachelor degree in 2015 and Doctoral degree in 2021 at Dalian University of Technology (DUT), China. After that, she worked as a Research Associate at The University of Western Australia. Her research experience includes advanced Computational Fluid Dynamics (CFD) technology, in-depth understanding of physics associated with wake dynamics and hydrodynamic forces of multiple structures under complex flow conditions, vortex-induced vibration, three-dimensional wake transitions and turbulent wave boundary layers.

More information about Dr. Chengjiao Ren’s research and publications may be found on her profile page at https://www.researchgate.net/profile/Chengjiao-Ren-2.

Authors:

Chengjiao Ren South China University of Technology
Ligong Zhang South China University of Technology
Zinan Liu South China University of Technology
Liang Cheng South China University of Technology
Fei He University of Oxford