Pivot location and mass ratio effects on flow-induced vibration of a fully passive flapping foil

Zhuo Wang, Lin Du, Jisheng Zhao, Mark C. Thompson, Xiaofeng Sun

Research output: Contribution to journalArticleResearchpeer-review


This paper reports on an extensive numerical investigation of the effects of pivot location and mass ratio (m= solid/fluid mass) on flow-induced vibration (FIV) of a foil undergoing fully passive two-degree-of-freedom (2-DOF) plunging and pitching motion in a two-dimensional free-stream flow. Here, the normalised pivot location is defined by x=xp∕c, with c the foil length and xp the distance to the foil leading edge. A comprehensive set of numerical simulations were conducted employing an Immersed Boundary Method at a Reynolds number of 400. By analysing the FIV dynamics for three selected mass ratios, m=5, 20 and 200, at two pivot locations, x=0.35 and 0.50, it is found that there are two types (type-I and type-II) of FIV responses, one is primarily a driven static instability while the other is strongly associated with vortex shedding. Interestingly, for x=0.50, which is close to the mass centre, increasing the mass ratio can favour suppression of the chaotic response. Importantly, it is shown that there exists a critical mass ratio, above which the foil oscillations are suddenly suppressed. The findings indicate that the combined effects of eccentricity and mass ratio on the foil dynamics can be profound.

Original languageEnglish
Article number103170
Number of pages18
JournalJournal of Fluids and Structures
Publication statusPublished - Jan 2021


  • Eccentricity
  • Fluid–structure interaction
  • Mass ratio

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