2010/06/09 by Theodore Y. Wu, Wu, Theodore Yaotsu
Engineering · Environmental Science · #Aerospace Engineering and Energy Systems #Biological Physics (physics.bio-ph) #Biomimetic flight and propulsion mechanisms #FOS: Physical sciences #Fish Ecology and Management Studies #Mathematical Physics (math-ph)
paper · pdf · doi:10.48550/arxiv.1006.1927
openalex publication_date 2010/06/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
This expository review is devoted to fish swimming and bird/insect flight. (i) The simple waving motion of an elongated flexible ribbon plate of constant width, immersed in a fluid at rest, propagating a wave distally down the plate to swim forward is first considered to provide a fundamental concept on energy conservation. It is generalized to include variations in body width and thickness, vortex shedding from appended dorsal, ventral and caudal fins to closely simulate fish swimming for which a nonlinear theory is presented for large-amplitude propulsion. (ii) For bird flight, the pioneering studies on oscillating rigid wings are briefed, followed by presenting a nonlinear unsteady theory for flexible wing with arbitrary variations in shape and trajectory with a comparative study with experiments. (iii) For insect flight, more recent advances are reviewed under aerodynamic theory and modeling, computational methods, and experiments, on forward and hovering flights with producing leading-edge vortex to give unsteady high lift. (iv) Prospects are explored on extracting intrinsic flow energy by fish and bird to gain thrust for propulsion. (v) The mechanical and biological principles are drawn together for unified studies on the energetics in deriving metabolic power for animal locomotion, leading to a surprising discovery that the hydrodynamic viscous drag on swimming fish is largely associated with laminar boundary layers, thus drawing valid and sound evidences for a resolution to the fish-swim paradox proclaimed by Gray (1936, 1968).