Wake structure and thrust generation of a flapping foil in two-dimensional flow

Research output: Contribution to journalJournal article – Annual report year: 2017Researchpeer-review

Documents

DOI

View graph of relations

We present a combined numerical (particle vortex method) and experimental (soap film tunnel) study of a symmetric foil undergoing prescribed oscillations in a two-dimensional free stream. We explore pure pitching and pure heaving, and contrast these two generic types of kinematics. We compare measurements and simulations when the foil is forced with pitching oscillations, and we find a close correspondence between flow visualisations using thickness variations in the soap film and the numerically determined vortex structures. Numerically, we determine wake maps spanned by oscillation frequency and amplitude, and we find qualitatively similar maps for pitching and heaving. We determine the drag–thrust transition for both pitching and heaving numerically, and we discuss it in relation to changes in wake structure. For heaving with low oscillation frequency and high amplitude, we find that the drag–thrust transition occurs in a parameter region with wakes in which two vortex pairs are formed per oscillation period, in contrast to the common transition scenario in regions with inverted von Kármán wakes.
Original languageEnglish
Article numberR4
JournalJournal of Fluid Mechanics
Volume812
Number of pages12
ISSN0022-1120
DOIs
Publication statusPublished - 2017
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Propulsion, Vortex shedding, Wakes/jets

Download statistics

No data available

ID: 128186402