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Lookup NU author(s): Dr Rameez BadhurshahORCiD, Dr Nara SrinilORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2026 The Author(s). Ocean environmental flow contains variable turbulence leading to the flow velocity fluctuation. Depending on the flow turbulence intensity, such randomness in the incoming flow could affect the occurrence of vortex-induced vibration (VIV) and associated fluid-structure interaction response. Previous studies have mostly dealt with VIV in steady incoming flow or only cross-flow VIV in turbulent incoming flow. In this study, the influence of free-stream turbulence on coupled cross-flow and in-line VIV is investigated through a phenomenological model based on the stochastic wake oscillators. Multi-degree-of-freedom VIV features of elastically mounted rigid cylinders and long flexible cylinders are discussed, with the latter exhibiting the dependence on the spatio-temporal variation and multi-modal contribution. Herein, a stochastic mean-reverting process is modelled by the Ornstein-Uhlenbeck differential equation, in which time histories of incoming flow velocities contain both the time-averaged and randomly fluctuating components constituting the turbulence intensity. These lead to a random fluctuation of vortex shedding frequencies and reduced velocities, affecting the hydrodynamic lift and drag forces and regulating the fluid-structure coupling terms through the stochastic wake oscillators. Model calibration is carried out based on available experimental data in the literature to establish baseline sets of empirical coefficients. Parametric investigations are carried out for rigid and long flexible cylinders undergoing two- and three-dimensional VIV, respectively. Depending on the flow turbulence intensity, reduced velocity parameter, mass-damping ratio, cable- or beam-dominated behaviour, and uniform or shear flow profile, numerical results highlight several VIV features in free-stream turbulent flows. For rigid cylinders, in-line VIV is inherently more governed by the free-stream turbulence than cross-flow VIV, entailing the highly modulated two-dimensional motion trajectories, particularly in a region outside the main lock-in or synchronisation. For long flexible cylinders, a peculiar spatial modal transition occurs in both in-line and cross-flow responses when varying the mean flow velocity with a high turbulence intensity, leading to an evolution of standing, travelling and mixed standing-travelling waves as well as the enhanced multi-modal participation in three-dimensional stochastic responses. Overall, the numerical prediction results reveal quantitative and qualitative effects of free-stream turbulence that should be recognised when considering practical turbulent flow conditions in the VIV analysis and design.
Author(s): Badhurshah R, Srinil N
Publication type: Article
Publication status: Published
Journal: Journal of Fluids and Structures
Year: 2026
Volume: 145
Print publication date: 01/08/2026
Online publication date: 28/04/2026
Acceptance date: 02/04/2018
Date deposited: 11/05/2026
ISSN (print): 0889-9746
ISSN (electronic): 1095-8622
Publisher: Academic Press
URL: https://doi.org/10.1016/j.jfluidstructs.2026.104588
DOI: 10.1016/j.jfluidstructs.2026.104588
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