Skip to main content
×
Home

Ultra-fast escape of a deformable jet-propelled body

  • G. D. Weymouth (a1) and M. S. Triantafyllou (a2)
Abstract
Abstract

In this work a cephalopod-like deformable body that fills an internal cavity with fluid and expels it to propel an escape manoeuvre, while undergoing a drastic external shape change through shrinking, is shown to employ viscous as well as mainly inviscid hydrodynamic mechanisms to power an impressively fast start. First, we show that recovery of added-mass energy enables a shrinking rocket in a dense inviscid flow to achieve greater escape speed than an identical rocket in a vacuum. Next, we extend the shrinking body results of Weymouth & Triantafyllou (J. Fluid Mech., vol. 702, 2012, pp. 470–487) to three-dimensional bodies and show that three hydrodynamic mechanisms must be combined to achieve rapid escape performance in a viscous fluid: added-mass energy recovery; flow separation elimination; and an optimized energy storage and recovery. In particular, we show that the mechanism of separation elimination achieved through rapid body shrinking, coordinated with the mechanism of recovering the initially imparted added-mass energy, is critical to achieving a high escape speed. Hence a flexible, collapsing body can be vastly superior to a rigid-shell jet-propelled body.

Copyright
Corresponding author
Email addresses for correspondence: weymouth@mit.edu, G.D.Weymouth@soton.ac.uk
References
Hide All
Anderson E. J. & Grosenbaugh M. A. 2005 Jet flow in steadily swimming adult squid. J. Expl Biol. 208, 11251146.
Anderson E. J., Wuinn W & deMont M. E. 2001 Hydrodynamics of locomotion in the squid Loligo pealei. J. Fluid Mech. 436, 249266.
Bartol I. K., Krueger P. S., Thompson J. T. & Stewart W. J. 2009 Pulsed jet dynamics of squid hatchlings at intermediate Reynolds numbers. J. Expl Biol. 212, 15061518.
Childress S., Spagnolie S. E. & Tokieda T. 2011 A bug on a raft: recoil locomotion in a viscous fluid. J. Fluid Mech. 669, 527556.
Childress S., Vanderberghe N. & Zhang J. 2006 Hovering of a passive body in an oscillating airflow. Phys. Fluids 18, 117103.
Dabiri J. O., Colin S. P. & Costello J. H. 2006 Fast-swimming hydromedusae exploit velar kinematics to form an optimal vortex wake. J. Expl Biol. 209, 20252033.
Daniel T. L. 1984 Unsteady aspects of aquatic locomotion. Am. Zool. 24 (1), 121134.
Domenici P., Blagburn J. M. & Bacon J. P. 2011a Animal escapology I: theoretical issues and emerging trends in escape trajectories. J. Expl Biol. 214, 24632473.
Domenici P., Blagburn J. M. & Bacon J. P. 2011b Animal escapology II: escape trajectory case studies. J. Expl Biol. 214, 24742494.
Domenici P. & Blake R. 1997 The kinematics and performance of fish fast-start swimming. J. Expl Biol. 200, 11651178.
Forsythe J. W. & Hanlon R. T. 1988 Behavior body patterning and reproductive biology of Octopus bimaculoides from California USA. Malacologia 29, 4155.
Gazzola M., van Rees W. M. & Koumoutsakos P. 2012 C-start: optimal start of larval fish. J. Fluid Mech. 698, 517.
Gosline J. M. & DeMont M. E. 1985 Jet-propelled swimming in squid. Sci. Am. 252, 96103.
Hoerner S. 1965 Fluid Dynamic Drag. Published by the author, Hoerner Fludi Dynamics, Bricktown, New Jersey.
Huffard C. L. 2006 Locomotion by Abdopus aculeatus (Cephalopoda: Octopodidae): walking the line between primary and secondary defenses. J. Expl Biol. 209, 36973707.
Kanso E., Marsden J. E., Rowley C. W. & Melli-Huber J. B. 2005 Locomotion of articulated bodies in a perfect fluid. J. Nonlinear Sci. 15, 255289.
Linden P. F. & Turner J. S. 2004 Optimal vortex rings and aquatic propulsion mechanisms. Proc. R. Soc. Lond. B 271, 647653.
Margolin L. G., Rider W. J. & Grinstein F. F. 2006 Modeling turbulent flow with implicit LES. J Turbul 7, 127.
Moslemi A. & Krueger P. S. 2011 The effect of Reynolds number on the propulsive efficiency of a biomorphic pulsed-jet underwater vehicle. Bioinsp. Biomim. 6, 026001.
Neumeister H., Ripley B., Preuss T. & Gilly W. F. 2000 Effects of remperature on escape jetting in the squid Loligo opalescens. J. Expl Biol. 203, 547557.
Packard A. 1969 Jet propulsion and the giant fibre response of Loligo. Nature 221, 875877.
Saffman P. G. 1967 Self-propulsion of a deformable body in a perfect fluid. J. Fluid Mech. 28, 385389.
Spagnolie S. E. & Shelley M. J. 2009 Shapechanging bodies in fluid: hovering, ratcheting, and bursting. Phys. Fluids 21, 013103.
Wells M. J. 1990 Oxygen extraction and jet propulsion in Cephalopods. Can. J. Zool. 68, 815824.
Weymouth G. D., Dommermuth D. G., Hendrickson K. & Yue D. K.-P. 2006 Advancements in Cartesian-grid methods for computational ship hydrodynamics. 26th Symposium on Naval Hydrodynamics, Rome, Italy, 17–22 September 2006.
Weymouth G. D. & Triantafyllou M. S. 2012 Global vorticity shedding for a shrinking cylinder. J. Fluid Mech. 702, 470487.
Weymouth G. D. & Yue D. K.-P. 2011 Boundary data immersion method for Cartesian-grid simulations of fluid-body interaction problems. J. Comput. Phys. 230, 16.
Wibawa M. S., Steele S. C., Dahl J. D., Rival D. E., Weymouth G. D. & Triantafyllou M. S. 2012 Global vorticity shedding for a vanishing wing. J. Fluid Mech. 695, 112134.
Williamson G. R. 1965 Underwater observations of the squid Illex illecebrosus Lesueur in Newfoundland waters. Can. Field Natur. 79, 239247.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×
MathJax

Keywords:

Metrics

Full text views

Total number of HTML views: 1
Total number of PDF views: 53 *
Loading metrics...

Abstract views

Total abstract views: 236 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 24th November 2017. This data will be updated every 24 hours.