Moving efficiently through water: aquatic animals
Aquatic organisms move effectively through water by maximizing propulsion efficiency.
|Biomimetic Application Ideas|
|Having a transport system that moves slowly by undulation rather than rotating helix model (propeller) could increase efficiency by at least 10%.|
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While the Froud efficiencies "vary in quality and involve differenty underlying assumptions and simplifications, the picture that emerges is satisfyingly consistent with our expectations."
"* Moving water with undulating body, beating wing, or swinging tail beats squeezing water out of a jet, as anticipated. A squid may jet fast, but when it wants to go far, it's more likely to use its fins.
"* The same undulating devices do better than systems that move water back-wards with a paddling system, with its alternating power and recovery strokes. We'll return to this comparison between 'lift-based' and 'drag-based' propulsion in chapter 13.
"*Bigger (or at least moderate size) is better than smaller. Except for one questionable datum for a bacterial flagellum, no creature below about a centimeter in length does better than ηf = 0.5. The pernicious effects of low Reynolds number (chapter 11) cannot be denied.
"*The broad hydrozoan medusae (essentially small jellyfish) may use jet propulsion, but they do it by pushing out an especially large volume (relative to their own) through a wide aperture. So they have a much higher m and lower v2 than the other jetters, and thus evade most of the difficulty inherent in equations (7.5) and (7.6)." (Vogel 2003:142-143)
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist
Application Ideas: Having a transport system that moves slowly by undulation rather than rotating helix model (propeller) could increase efficiency by at least 10%.
Industrial Sector(s) interested in this strategy: Transportation, aerospace, marine architecture and engineering