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J R Soc Interface. 2018 Feb;15(139). pii: 20170828. doi: 10.1098/rsif.2017.0828.

Shark skin-inspired designs that improve aerodynamic performance.

Author information

1
Harvard University John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA 02138, USA.
2
Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
3
College of Engineering and Computing, University of South Carolina, Columbia, SC 29208, USA.
4
Wyss Institute for Biologically Inspired Engineering, Cambridge, MA 02138, USA.
5
Harvard University John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA 02138, USA bertoldi@seas.harvard.edu.
6
Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA glauder@oeb.harvard.edu.

Abstract

There have been significant efforts recently aimed at improving the aerodynamic performance of aerofoils through the modification of their surfaces. Inspired by the drag-reducing properties of the tooth-like denticles that cover the skin of sharks, we describe here experimental and simulation-based investigations into the aerodynamic effects of novel denticle-inspired designs placed along the suction side of an aerofoil. Through parametric modelling to query a wide range of different designs, we discovered a set of denticle-inspired surface structures that achieve simultaneous drag reduction and lift generation on an aerofoil, resulting in lift-to-drag ratio improvements comparable to the best-reported for traditional low-profile vortex generators and even outperforming these existing designs at low angles of attack with improvements of up to 323%. Such behaviour is enabled by two concurrent mechanisms: (i) a separation bubble in the denticle's wake altering the flow pressure distribution of the aerofoil to enhance suction and (ii) streamwise vortices that replenish momentum loss in the boundary layer due to skin friction. Our findings not only open new avenues for improved aerodynamic design, but also provide new perspective on the role of the complex and potentially multifunctional morphology of shark denticles for increased swimming efficiency.

KEYWORDS:

aerofoil; denticle; hydrodynamics; lift; shark skin; vortex generator

PMID:
29436512
PMCID:
PMC5832729
[Available on 2019-02-01]
DOI:
10.1098/rsif.2017.0828

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