Optimal Strouhal number for swimming animals
By Christophe Eloy. 2011
299 citations recorded by the source corpus.
Abstract To evaluate the swimming performances of aquatic animals, an important dimensionless quantity is the Strouhal number, St = fA / U , with f the tail-beat frequency, A the peak-to-peak tail amplitude, and U the swimming velocity. Experiments with flapping foils have exhibited maximum propulsive efficiency in the interval 0.25 St 0.35 and it has been argued that animals likely evolved to swim in the same narrow interval. Using Lighthill's elongated-body theory to address undulatory propulsion, it is demonstrated here that the optimal Strouhal number increases from 0.15 to 0.8 for animals spanning from the largest cetaceans to the smallest tadpoles. To assess the validity of this model, the swimming kinematics of 53 different species of aquatic animals have been compiled from the literature and it shows that their Strouhal numbers are consistently near the predicted optimum.
Subfields: Aerospace Engineering, Nature and Landscape Conservation
View Paper: https://www.semanticscholar.org/paper/f8209c33d9abfd5db116fd698630700fa64661ec
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In Aerospace Engineering
In Nature and Landscape Conservation
Citations in the corpus
- On the best design for undulatory swimming (2013, methodology): “The same prediction can be reached with an inviscid analysis in the linear (Lighthill 1971) or the weakly nonlinear limit (Eloy 2012).”
- Direct measurement of thrust and efficiency of an airfoil undergoing pure pitching (2015, background): “…mechanics as a tool to understand aspects of biology, such as the theoretical model of fish swimming by Lighthill (1970) and calculation of optimal propulsion parameters for aquatic animals (see Triantafyllou, Triantafyllou & Grosenbaugh 1993; Triantafyllou, Triantafyllou & Yue 2000; Eloy 2012).”
- Undulatory and oscillatory swimming (2019, background): “Similarly, Taylor 874 P1-6 (2018) writes that an explanation of propulsive efficiency given only in terms of the wake feels a little incomplete, and notes that Eloy (2012) suggested that efficient development of the wake may be a consequence, rather than a cause, of efficient propulsion.”