The performance of a flapping foil for a self-propelled fishlike body

Autor: Giorgio Graziani, Damiano Paniccia, Renzo Piva, Luca Padovani
Rok vydání: 2021
Předmět:
Zdroj: Scientific Reports
Scientific Reports, Vol 11, Iss 1, Pp 1-7 (2021)
ISSN: 2045-2322
Popis: Several fish species propel by oscillating the tail, while the remaining part of the body essentially contributes to the overall drag. Since in this case thrust and drag are in a way separable, most attention was focused on the study of propulsive efficiency for flapping foils under a prescribed stream. We claim here that the swimming performance should be evaluated, as for undulating fish whose drag and thrust are severely entangled, by turning to self-propelled locomotion to find the proper speed and the cost of transport for a given fishlike body. As a major finding, the minimum value of this quantity corresponds to a locomotion speed in a range markedly different from the one associated with the optimal efficiency of the propulsor. A large value of the feathering parameter characterizes the minimum cost of transport while the optimal efficiency is related to a large effective angle of attack. We adopt here a simple two-dimensional model for both inviscid and viscous flows to proof the above statements in the case of self-propelled axial swimming. We believe that such an easy approach gives a way for a direct extension to fully free swimming and to real-life configurations.
Databáze: OpenAIRE
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