The three-dimensional wake of a cylinder undergoing a combination of translational and rotational oscillation in a quiescent fluid

M. Nazarinia, D. Lo Jacono, M. C. Thompson, J. Sheridan

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Previous two-dimensional numerical studies have shown that a circular cylinder undergoing both oscillatory rotational and translational motions can generate thrust so that it will actually self-propel through a stationary fluid. Although a cylinder undergoing a single oscillation has been thoroughly studied, the combination of the two oscillations has not received much attention until now. The current research reported here extends the numerical study of Blackburn [Phys. Fluids 11, L4 (1999)] both experimentally and numerically, recording detailed vorticity fields in the wake and using these to elucidate the underlying physics, examining the three-dimensional wake development experimentally, and determining the three-dimensional stability of the wake through Floquet stability analysis. Experiments conducted in the laboratory are presented for a given parameter range, confirming the early results from Blackburn [Phys. Fluids 11, L4 (1999)]. In particular, we confirm the thrust generation ability of a circular cylinder undergoing combined oscillatory motions. Importantly, we also find that the wake undergoes three-dimensional transition at low Reynolds numbers (Re similar or equal to 100) to an instability mode with a wavelength of about two cylinder diameters. The stability analysis indicates that the base flow is also unstable to another mode at slightly higher Reynolds numbers, broadly analogous to the three-dimensional wake transition mode for a circular cylinder, despite the distinct differences in wake/mode topology. The stability of these flows was confirmed by experimental measurements.

Original languageEnglish
Article numberARTN 064101
Number of pages7
JournalPhysics of Fluids
Volume21
Issue number6
DOIs
Publication statusPublished - Jun 2009

Keywords

  • VORTICITY
  • TRANSITION
  • numerical analysis
  • FLOW
  • ACCURACY
  • flow instability
  • confined flow
  • INSTABILITIES
  • FLOQUET STABILITY ANALYSIS
  • wakes
  • fluid oscillations
  • LOW KEULEGAN-CARPENTER
  • ROTARY OSCILLATION
  • laminar flow
  • CIRCULAR-CYLINDER
  • vortices
  • NUMBERS

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