Instability-driven frequency decoupling between structure dynamics and wake fluctuations

Yaqing Jin, Jin Tae Kim, Leonardo Patricio Chamorro Chavez

Research output: Contribution to journalArticle

Abstract

Flow-induced dynamics of flexible structures is, in general, significantly modulated by periodic vortex shedding. Experiments and numerical simulations suggest that the frequencies associated with the dominant motions of structures are highly coupled with those of the wake under low-turbulence uniform flow. Here we present experimental evidence that demonstrates a significant decoupling between the dynamics of simple structures and wake fluctuations for various geometries, Reynolds numbers, and mass ratios. High-resolution particle tracking velocimetry and hot-wire anemometry are used to quantitatively characterize the dynamics of the structures and wake fluctuations; a complementary planar particle image velocimetry measurement is conducted to illustrate distinctive flow patterns. Results show that for structures with directional stiffness, von Kármán vortex shedding might dominate the wake of bodies governed by natural-frequency motion. This phenomenon can be a consequence of Kelvin-Helmholtz instability, where the structural characteristics of the body dominate the oscillations.

Original languageEnglish (US)
Article number044701
JournalPhysical Review Fluids
Volume3
Issue number4
DOIs
StatePublished - Apr 13 2018

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ASJC Scopus subject areas

  • Computational Mechanics
  • Modeling and Simulation
  • Fluid Flow and Transfer Processes

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