Detection and tracking of vortex phenomena using Lagrangian coherent structures

Yangzi Huang, Melissa A Green

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

The formation and shedding of vortices in two vortex-dominated flows around an actuated flat plate are studied to develop a better method of identifying and tracking coherent structures in unsteady flows. The work automatically processes data from the 2D simulation of a flat plate undergoing a 45∘ pitch-up maneuver, and from experimental particle image velocimetry data in the wake of a continuously pitching trapezoidal panel. The Eulerian Γ1, Γ2, and Q functions, as well as the Lagrangian finite-time Lyapunov exponent are applied to identify both the centers and boundaries of the vortices. The multiple vortices forming and shedding from the plates are visualized well by these techniques. Tracking of identifiable features, such as the Lagrangian saddle points, is shown to have potential to identify the timing and location of vortex formation, shedding, and destruction more precisely than by only studying the vortex cores as identified by the Eulerian techniques.

Original languageEnglish (US)
Article number147
JournalExperiments in Fluids
Volume56
Issue number7
DOIs
StatePublished - Jul 25 2015

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Keywords

  • Finite-time Lyapunov exponent
  • Unsteady aerodynamics
  • Vortex detection

ASJC Scopus subject areas

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

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