Flow-induced vibration on two tandem cylinders of different diameters and spacing ratios

Hamid Hassan Khan, Md Didarul Islam, Yap Yit Fatt, Isam Janajreh, Md Mahbub Alam

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24 Scopus citations


This work numerically investigates flow-induced vibration (FIV) of two tandem cylinders of unequal diameters at a Reynolds number of 100 and at a range of reduced velocity 2 − 10. Particular attention is paid to assimilating the effects of the cylinder diameter ratio (0.2 − 1) and the cylinder spacing ratio 1.5, 3.5 and 5.5 on vibration responses, frequency responses, lock-in, and wake structure. The cylinder-to-fluid mass ratio is considered as one, and the damping coefficient is set to zero to attain maximum oscillation amplitude. The obtained results reveal that FIV is highly sensitive to both diameter and spacing ratios, and the wake interference involved is intricate. With a decrease in diameter ratio, the upstream cylinder oscillation is affected due to a change in its effective Reynolds number while its wake induces a significant effect on the downstream cylinder. The lowest diameter ratio of 0.2 exhibits a de-energized wake suppressing the oscillation of the downstream cylinder. At a moderate diameter ratio of 0.6, suppressed and excited oscillations of the downstream cylinder are observed at spacing ratios 1.5 and 3.5, respectively.

Original languageBritish English
Article number111747
JournalOcean Engineering
StatePublished - 15 Aug 2022


  • Flow pattern
  • Flow-induced vibration (FIV)
  • Multiple cylinders
  • Tandem arrangement
  • Unequal-diameter


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