Three-dimensional finite-time lyapunov exponent field in the wake of an oscillating trapezoidal pitching panel

Rajeev Kumar, Ayodeji Bode-Oke, Justin King, Geng Liu, Haibo Dong, Melissa A Green

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Fish and other aquatic animals generate thrust by oscillating their fins and flukes creating a highly three-dimensional and complex wake that is characterized by spanwise compression, transverse expansion, wake breakdown, etc. Understanding of wake dynamics is important in order to design an efficient bio-inspired propulsion system. Lagrangian analysis using the finite-time Lyapunov exponent (FTLE) field was carried out on experimentally recorded three-dimensional data in the wake of an oscillating trapezoidal panel modeling a fish caudal fin in a Strouhal number range of 0.17 - 0.56. Behavior of the wake structure observed in the isosurfaces and contours in the three-dimensional FTLE field was compared with the measured forces generated by the panel from a numerical simulation. Occurrences of peaks and troughs of thrust correlated with the release of saddle points associated with the formation and the shedding of the spanwise vortices at the trailing edge. The location of vortex disintegration, which is observed further downstream, was observed to correspond with low momentum flow regions, bifurcated wake structure, and the merger of saddle points from two consecutive spanwise structures.

Original languageEnglish (US)
Title of host publication47th AIAA Fluid Dynamics Conference, 2017
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624105005
StatePublished - 2017
Event47th AIAA Fluid Dynamics Conference, 2017 - Denver, United States
Duration: Jun 5 2017Jun 9 2017

Other

Other47th AIAA Fluid Dynamics Conference, 2017
CountryUnited States
CityDenver
Period6/5/176/9/17

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ASJC Scopus subject areas

  • Aerospace Engineering
  • Engineering (miscellaneous)

Cite this

Kumar, R., Bode-Oke, A., King, J., Liu, G., Dong, H., & Green, M. A. (2017). Three-dimensional finite-time lyapunov exponent field in the wake of an oscillating trapezoidal pitching panel. In 47th AIAA Fluid Dynamics Conference, 2017 American Institute of Aeronautics and Astronautics Inc, AIAA.