Affiliations: Graduate School of Engineering, Toyo University,
2100Kujirai, Kawagoe, Saitama, 350-8585, Japan. E-mail:
dn0700049@toyonet.toyo.ac.jp | Faculty of Engineering, Toyo University, 2100Kujirai,
Kawagoe, Saitama, 350-8585, Japan
Abstract: The purpose of this study is to understand the propulsion mechanism
of a jellyfish during its swimming. We observed the motion of a jellyfish
(Aurelia aurita) by a motion-capture camera, and measured the vector field of
flow around a jellyfish by using a PIV (Particle Image Velocimetry)
measurement. A jellyfish is considered to be principally propelled by a jet at
the contracting phase of its motion. If that is true, it is interesting that a
jellyfish never stops traveling even at the expanding phase. We found that a
vortex ring with the opposite vorticity to shed vortex ring was inside a
jellyfish body in the expanding phase. We discussed a cause of an increase in
thrust force and keeping constant speed in the expanding phase.