title: Spontaneous symmetry breaking of a hinged flapping filament generates lift.
abstract: Elastic filamentous structures found on swimming and flying organisms are versatile in function, rendering their precise contribution to locomotion difficult to assess. We show in this Letter that a single passive filament hinged on the rear of a bluff body placed in a stream can generate a net lift force without increasing the mean drag force on the body. This is a consequence of spontaneous symmetry breaking in the filament's flapping dynamics. The phenomenon is related to a resonance between the frequency associated with the von Kármán vortex street developing behind the bluff body and the natural frequency of the free bending vibrations of the filament.
authors.affiliation: DICCA, University of Genova, Genova, Italy.
authors.forename: Shervin
authors.initials: S
authors.lastname: Bagheri
authors.forename: Andrea
authors.initials: A
authors.lastname: Mazzino
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bottaro