Accelerating fishes increase propulsive efficiency by modulating vortex ring geometry

Otar Akanyeti, Joy Putney, Yuzo R. Yanagitsuru, George V. Lauder, William J. Stewart, James C. Liao

Research output: Contribution to journalArticlepeer-review

48 Citations (SciVal)
135 Downloads (Pure)


Swimming animals need to generate propulsive force to overcome drag, regardless of whether they swim steadily or accelerate forward. While locomotion strategies for steady swimming are well characterized, far less is known about acceleration. Animals exhibit many different ways to swim steadily, but we show here that this behavioral diversity collapses into a single swimming pattern during acceleration regardless of the body size, morphology, and ecology of the animal. We draw on the fields of biomechanics, fluid dynamics, and robotics to demonstrate that there is a fundamental difference between steady swimming and forward acceleration. We provide empirical evidence that the tail of accelerating fishes can increase propulsive efficiency by enhancing thrust through the alteration of vortex ring geometry. Our study provides insight into how propulsion can be altered without increasing vortex ring size and represents a fundamental departure from our current understanding of the hydrodynamic mechanisms of acceleration. Our findings reveal a unifying hydrodynamic principle that is likely conserved in all aquatic, undulatory vertebrates
Original languageEnglish
Pages (from-to)13828-13833
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number52
Early online date11 Dec 2017
Publication statusPublished - 26 Dec 2017


  • acceleration
  • undelatory swimming
  • vortex ring
  • fish
  • hydrodynamics


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