Hydrodynamic Performance of Two-Dimensional Undulating Foils in Triangular Formation

As inspired by studies of fish schooling in literature, this work investigates hydrodynamic performance of a two-dimensional undulating-foil triad in viscous flows via numerical simulation. The chord of foil oscillates in the form of a streamwise traveling wave. The triad is in triangular formation,...

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Bibliographic Details
Published in:Journal of mechanics 2011-06, Vol.27 (2), p.177-190
Main Author: Chung, M.-H.
Format: Article
Language:English
Subjects:
Analysis
Fluid mechanics
Studies
Viscosity
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Summary:As inspired by studies of fish schooling in literature, this work investigates hydrodynamic performance of a two-dimensional undulating-foil triad in viscous flows via numerical simulation. The chord of foil oscillates in the form of a streamwise traveling wave. The triad is in triangular formation, i.e., two foils followed by one. A series of triad configuration are computed assuming the same wave speed, amplitude, and frequency of chord traveling wave for each foil. The results show that, to achieve highest thrust efficiency, the two leading foils should separate from each other by 0.4 chord length, perform antiphase undulating motion, and the leading edge of the trailing foil stay 0.2 chord length in front of the trailing edges of the leading foils. An underlining mechanism, vortex pair shedding from the leading foil interacting with boundary-layer vorticity field of the trailing foil, has been identified to explain the efficiency enhancement. This optimal triad configuration is different from that obtained in a previous potential flow analysiss.
ISSN:1727-7191
1811-8216
DOI:10.1017/jmech.2011.21