Control of vortex rings for manoeuvrability

Document Type

Article

Publication Title

Journal of the Royal Society Interface

Publication Date

7-6-2015

Abstract

Manoeuvrability is critical to the success of many species. Selective forces acting over millions of years have resulted in a range of capabilities currently unmatched by machines. Thus, understanding animal control of fluids for manoeuvring has both biological and engineering applications. Within inertial fluid regimes, propulsion involves the formation and interaction of vortices to generate thrust.We use both volumetric and planar imaging techniques to quantify how jellyfish (Aurelia aurita) modulate vortex rings during turning behaviour. Our results show that these animals distort individual vortex rings during turns to alter the force balance across the animal, primarily through kinematicmodulation of the bellmargin.We find that only a portion of the vortex ring separates from the body during turns, which may increase torque. Using a fluorescent actin staining method,we demonstrate the presence of radial muscle fibres lining the bell along the margin. The presence of radial muscles provides a mechanistic explanation for the ability of scyphomedusae to alter their bell kinematics to generate non-symmetric thrust for manoeuvring. These results illustrate the advantage of combining imaging methods and provide new insights into the modulation and control of vorticity for low-speed animal manoeuvring.

Volume

12

Issue

108

DOI

10.1098/rsif.2015.0389

ISSN

17425689

E-ISSN

17425662

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