Start of funding 01.01.2015

What do a bacterial cell and a bird have in common? Commonalities in propulsion and transport mechanisms across multiple flow regimes

Prof. Dr. Walter Zimmermann
University of Bayreuth
Lehrstuhl für Theoretische Physik 1

Prof. Dr. Eva Kanso
University of Southern California, Los Angeles
Department of Aerospace and Mechanical Engineering and Material Science



Flapping wing motions produce lift forces that allow insects and birds to fly forward or hover in place. As a proxy to flapping flight, we study a rigid Λ-shaped object in an oscillating uniform up- and down flow for larger values of the Reynolds number. The up-down asymmetry in the object leads to different flow profiles during each half period which keeps the Λ-shaped object aloft. The effective hovering conditions and the stability of hovering are analysed as a function of the object shape. We expect elementary insights about flying insects and birds.

A very small rigid Λ-shaped object in an alternating uniform up/down flow of a viscous fluid (zero Reynolds number) does not hover in a gravitational field. However, a flexible a Λ-shaped object has different shapes during up- and downward fluid motion and we expect even in the limit of small values of the Reynolds number a hovering effect in an alternating uniform flow, which may be useful for particle separation.