Hovering of a passive body in an oscillating airflow

Stephen Childress, Nicolas Vandenberghe, Jun Zhang

Research output: Contribution to journalArticle

Abstract

Small flexible bodies are observed to hover in an oscillating air column. The air is driven by a large speaker at frequencies in the range 10-65 Hz at amplitudes 1-5 cm. The bodies are made of stiffened tissue paper, bent to form an array of four wings, symmetric about a vertical axis. The flapping of the wings, driven by the oscillating flow, leads to stable hovering. The hovering position of the body is unstable under free fall in the absence of the airflow. Measurements of the minimum flow amplitude as a function of flow frequency were performed for a range of self-similar bodies of the same material. The optimal frequency for hovering is found to vary inversely with the size. We suggest, on the basis of flow visualization, that hovering of such bodies in an oscillating flow depends upon a process of vortex shedding closely analogous to that of an active flapper in otherwise still air. A simple inviscid model is developed illustrating some of the observed properties of flexible passive hoverers at high Reynolds number.

Original languageEnglish (US)
Article number117103
JournalPhysics of Fluids
Volume18
Issue number11
DOIs
StatePublished - Nov 2006

Fingerprint

hovering
Oscillating flow
oscillating flow
Air
wings
air
Vortex shedding
flexible bodies
Flow visualization
flapping
free fall
vortex shedding
flow visualization
high Reynolds number
Reynolds number
Tissue

ASJC Scopus subject areas

  • Mechanics of Materials
  • Computational Mechanics
  • Physics and Astronomy(all)
  • Fluid Flow and Transfer Processes
  • Condensed Matter Physics

Cite this

Childress, S., Vandenberghe, N., & Zhang, J. (2006). Hovering of a passive body in an oscillating airflow. Physics of Fluids, 18(11), [117103]. https://doi.org/10.1063/1.2371123

Hovering of a passive body in an oscillating airflow. / Childress, Stephen; Vandenberghe, Nicolas; Zhang, Jun.

In: Physics of Fluids, Vol. 18, No. 11, 117103, 11.2006.

Research output: Contribution to journalArticle

Childress, S, Vandenberghe, N & Zhang, J 2006, 'Hovering of a passive body in an oscillating airflow', Physics of Fluids, vol. 18, no. 11, 117103. https://doi.org/10.1063/1.2371123
Childress, Stephen ; Vandenberghe, Nicolas ; Zhang, Jun. / Hovering of a passive body in an oscillating airflow. In: Physics of Fluids. 2006 ; Vol. 18, No. 11.
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