The role of tail resonance in thrust production and wake formation

Megan C. Leftwich, Alexander J. Smits

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A robotic lamprey with a flexible tail is used to investigate the influence of resonance on the wake structure and thrust production during anguilliform swimming, based on the silver lamprey, Ichthyomyzon unicuspis. A programmable microcomputer actuates 11 servomotors that produce a traveling wave along the length of the lamprey body. The shape of the tail is taken from a CT scan of the silver lamprey. The flexible tail is constructed of PVC gel. PIV measurements taken with the tail flapping at its resonant frequency and at twice this value show that resonance greatly enhances the coherence of the wake structures. Momentum balance calculations reveal that at resonance the tail is producing significantly more thrust-there is a 96% increase. In both cases, the main wake structure is a pair of vortices shed each half cycle (a 2P wake structure). At resonance these pairs are clearly defined and appear in a reproducible location. However, at twice the resonant frequency, the main vortices are composed of several smaller vortical structures. The vortices in the resonant wake retain coherence further downstream than the non-resonant wake structures.

Original languageEnglish (US)
Title of host publication41st AIAA Fluid Dynamics Conference and Exhibit
StatePublished - Dec 1 2011
Event41st AIAA Fluid Dynamics Conference and Exhibit 2011 - Honolulu, HI, United States
Duration: Jun 27 2011Jun 30 2011


Other41st AIAA Fluid Dynamics Conference and Exhibit 2011
Country/TerritoryUnited States
CityHonolulu, HI

All Science Journal Classification (ASJC) codes

  • Fluid Flow and Transfer Processes
  • Energy Engineering and Power Technology
  • Aerospace Engineering
  • Mechanical Engineering


Dive into the research topics of 'The role of tail resonance in thrust production and wake formation'. Together they form a unique fingerprint.

Cite this