Drag analysis with a self-propelled flexible swimmer

David Gross, Yann Roux, Christophe Raufaste, and Argentina Médéric
Phys. Rev. Fluids 6, 053101 – Published 3 May 2021

Abstract

Fish swim by undulating their body to ensure propulsion. In steady state, thrust is balanced by a total drag force, whose dominant terms depend on the Reynolds number and on the flow regime. If skin friction prevails on pressure drag in the laminar regime, and conversely in the turbulent regime, it is not clear how important is the contribution of the vortex-induced drag in both regimes. In this article, we tackle both flow regimes within the same numerical framework to address this question and the relevant scaling laws at play. In particular, we show in the turbulent regime that the combination of both the pressure and vortex-induced drags sets the Strouhal number between 0.2 and 0.4 following the thrust and drag balance, in very good agreement with natural swimmers. In the laminar regime, the vortex-induced drag can be neglected in most cases. If not, we rationalize the correction and show that our two-dimensional swimmer needs to account for a significant amplification of the drag force to match the biological data.

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  • Received 28 October 2020
  • Accepted 29 March 2021

DOI:https://doi.org/10.1103/PhysRevFluids.6.053101

©2021 American Physical Society

Physics Subject Headings (PhySH)

Physics of Living Systems

Authors & Affiliations

David Gross1, Yann Roux1, Christophe Raufaste2,3, and Argentina Médéric2,*

  • 1MyCFD S.A.S., 1300 Route des Cretes, 06560 Valbonne, France
  • 2Université Côte d'Azur, CNRS, INPHYNI, 06100 Nice, France
  • 3Institut Universitaire de France (IUF), Paris, France

  • *Author to whom correspondence should be addressed

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Issue

Vol. 6, Iss. 5 — May 2021

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