Effect of pulsatile flow on hydrodynamic characteristics of vortex induced vibration of square cylinder

• Published in: Ocean engineering 2023-12, Vol.289, p.116290, Article 116290
• Main Authors: Masood, Saif, Khan, Mohammad Athar, Anwer, Syed Fahad, Hasan, Nadeem, Ali, Rashid
• Format: Article
• Language: English
• ISSN: 0029-8018
• DOI: 10.1016/j.oceaneng.2023.116290

Vortex Induced Vibration (VIV) of an elastically mounted square cylinder subjected to pulsatile flow conditions is solved numerically for Reynolds number (Re = 100) and low mass ratio (Mred = 2). The focus of the present work is on investigating the effects of pulsatile frequency on the response of the cylinder. Effects of variation in Keulegan-Carpenter number, KC ϵ [10- 40, step of 10] and reduced velocity, Ured, ϵ [3-25, step of 1], on hydrodynamic characteristics is studied. An Arbitrary-Lagrangian Euler (ALE) formulation is used to write the governing equations in two space dimensions. Maximum cross-flow displacement is observed for Ured = 7 for KC=10. It is found that, the lock-in becomes slightly wider with increase in KC. Different regimes like Initial Branch , Lower Branch and desynchronized have been identified for all KC. Beyond KC = 20, cylinder starts to vibrate with the pulsatile frequency. Moreover, in the Lock-in zone flow amplitude is not always enhanced, and it sometimes gets reduced. This is basically due to state of synchronization between displacement and forcing. For all KCs, in-phase and out-of-phase regimes were also identified for X and Y-direction displacements. Wake width and vortex strength are maximum at the lock-in. •Different flow branches are identified for the first time in a pulsatile flow.•Vortex formation length is shortest in the lock-in phase.•Wake width and vortex strength are maximum at the lock-in.•2S mode of vortex shedding is observed for one vibration cycle for all cases.•Effect of pulsatile flow on vortex induced vibration of square cylinder.