منابع مشابه
'Optimal' vortex rings and aquatic propulsion mechanisms.
Fishes swim by flapping their tail and other fins. Other sea creatures, such as squid and salps, eject fluid intermittently as a jet. We discuss the fluid mechanics behind these propulsion mechanisms and show that these animals produce optimal vortex rings, which give the maximum thrust for a given energy input. We show that fishes optimize both their steady swimming efficiency and their abilit...
متن کاملOptimal Vortex Formation as a Unifying Principle in Biological Propulsion
I review the concept of optimal vortex formation and examine its relevance to propulsion in biological and bio-inspired systems, ranging from the human heart to underwater vehicles. By using examples from the existing literature and new analyses, I show that optimal vortex formation can potentially serve as a unifying principle to understand the diversity of solutions used to achieve propulsion...
متن کاملVortex Rings in Bio-inspired and Biological Jet Propulsion
Pulsed-jets are commonly used for aquatic propulsion, such as squid and jellyfish locomotion. The sudden ejection of a jet with each pulse engenders the formation of a vortex ring through the roll-up of the jet shear layer. If the pulse is too long, the vortex ring will stop forming and the remainder of the pulse is ejected as a trailing jet. Recent results from mechanical pulsedjets have demon...
متن کاملPhysics of Rheologically-Enhanced Propulsion: Different Strokes in Generalized Stokes
Shear-thinning is an important rheological property of many biological fluids, such as mucus, whereby the apparent viscosity of the fluid decreases with shear. Certain microscopic swimmers have been shown to progress more rapidly through shear-thinning fluids, but is this behavior generic to all microscopic swimmers, and what are the physics through which shear-thinning rheology affects a swimm...
متن کاملSwimming propulsion forces are enhanced by a small finger spread.
The main aim of this study was to investigate the effect of finger spread on the propulsive force production in swimming using computational fluid dynamics. Computer tomography scans of an Olympic swimmer hand were conducted. This procedure involved three models of the hand with differing finger spreads: fingers closed together (no spread), fingers with a small (0.32 cm) spread, and fingers wit...
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ژورنال
عنوان ژورنال: Journal of Fluid Mechanics
سال: 2010
ISSN: 0022-1120,1469-7645
DOI: 10.1017/s0022112010004908