Short-wave instability growth in closely spaced vortex pairs

Nicholas Boustead, Kris Ryan, Gregory Sheard

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Abstract

The growth of short-wave elliptical instabilities in a Lamb-Oseen vortex pair subject to non-uniform strain fields at close vortex spacing is considered using direct numerical simulation at a Reynolds number Re = 20000. A linear stability analysis demonstrates that with reduced vortex spacing the growth rate of all axial wave-numbers is enhanced relative to that of the fastest-growing mode. A coupling of vortices is observed at close vortex spacing, which may lead to improved non-linear instability growth, and the development of fluid cross-over regions. These fluid cross-over regions are shown to be products of a linear growth regime.

Original languageEnglish
Pages (from-to)276-283
Number of pages8
JournalProgress in Computational Fluid Dynamics
Volume10
Issue number5-6
DOIs
Publication statusPublished - 2010

Keywords

  • aircraft wakes
  • elliptic instability
  • fluid cross-over
  • growth rate
  • Lamb-Oseen
  • linear stability analysis
  • vortex pair

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