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Biomimetic Designed Surfaces for Growth Suppression of Biofilm-Inspired Sharkskin Denticles
Published in Akihiro Miyauchi, Masatsugu Shimomura, Biomimetics, 2023
Mariko Miyazaki, Akihiro Miyauchi
As pointed out by Vincent et al., the ways of building functional structures are different between biology and technology [1]. The surfaces of living matter have evolved into various functional 3D structures that are beyond human approach [2]. Biomimetics, that seeks sustainable solutions for practical problems by emulating nature's time-tested patterns, functions and strategies, has developed remarkably in recent years [3]. For example, sharkskin, as illustrated in Fig. 14.1, is covered with numerous small tooth-like elements, termed dermal denticles (“denticles” hereafter) [4, 5]. The hydrodynamic function of sharkskin has been investigated for more than 30 years with the hypothesis that the microstructure of denticles, i.e., the minute projections, passively controls turbulent flow and reduces drag [6–13].
Biomimicry
Published in Rachel Beth Egenhoefer, Routledge Handbook of Sustainable Design, 2017
There are many familiar examples of biomimicry. Corrugation, the folding pattern seen inside corrugated cardboard and in corrugated roofing, emulates the sea scallop’s strategy for getting more stiffness out of a piece of material, making it more resistant to bending without adding more mass. Velcro®, the ubiquitous hook-and-loop fastener, was inspired by the common burr. After repeatedly pulling burrs out of his dog’s fur, Swiss engineer George de Mestral realized that burrs represent a fantastic dry reuseable adhesive. The sharkskin swimsuit used by Michael Phelps during his 2004 Olympic victories (Science in the News) has a surface that is not smooth but rather covered with scales patterned after the scale-like denticles found on a shark (Smithsonian National Museum of Natural History, 2015).
Wearable electronic textiles
Published in Textile Progress, 2019
David Tyler, Jane Wood, Tasneem Sabir, Chloe McDonnell, Abu Sadat Muhammad Sayem, Nick Whittaker
A well-known textile product was the sharkskin suit, developed and worn by members of the US swimming team for the 2008 Olympics in Beijing. The idea behind this technical fabric was to mimic sharkskin denticles to reduce drag and therefore enhance the swimmer’s performance in the water. Apparently, sharkskin denticles actually increase drag, but by studying the mechanical effects of water and the athlete’s performance in relation to drag reduction and force, design teams at Speedo were able to design and develop the inspiration for Speedo’s® Fastskin™ swimsuits. Furthermore, researchers have studied polar bear’s unique hair fibres and discovered them to be hollow and act as fibre-optic transmitters. The hairs capture sunlight, transferring heat beneath the white hair to the black skin, creating a thermal barrier against the harsh conditions these mammals live in. Other researchers have experimented with colouration methods based on what happens in butterfly wings.
Reducing drag force on polyester fabric through superhydrophobic surface via nano-pretreatment and water repellent finishing
Published in The Journal of The Textile Institute, 2018
N. Norouzi, A. A. Gharehaghaji, M. Montazer
Modern swimsuits have a design based on the structure of sharkskin. Careful studies in test pools showed that sharks can slip through the water with about 10% less energy expenditure than a fish with a perfectly smooth skin. These tests have allowed manufactures to design swimsuits made of artificial sharkskin. The sportswear company, Speedo, has developed a material called ‘Fastskin’ (George, Rodrigues, Mathur, Chidangil, & George, 2016).
Parametric investigation of drag reduction for marine vessels using air-filled dimpled surfaces
Published in Ships and Offshore Structures, 2018
G. Q. Zhang, J. Schlüter, X. Hu
Pooria et al. (2016) had conducted an experimental and computational approach to determine the residual resistance of a 1.5 m ship model in the series 60 category. The corresponding verification had shown the capability of the computational method due to the boundary layer simulation around the body. Matveev (2012) had studied the effect of the hull transom on the properties of an air cavity formed behind a wedge by a potential flow model. It is found that the air-cavity properties deteriorate when it is placed close to the transom, resulting in lower-pressure cavities with increased wedge pressure drag and larger amplitudes of waves behind the transom. The length of the longest cavity that can be created at a given speed and wedge geometry decrease in the vicinity of the transom. Latorre (1997), Butuzov et al. (1999) and Matveev (2005) have successfully developed several types of air-cavity ships. For an air cavity formed under a horizontal plate, Butuzov (1971) pioneered and developed the idea that the ventilated flow under a ship's bottom can be described using cavitation theory. Matveev et al. (2009) have also, respectively, conducted the experimental and simulated studies for the air-ventilated cavities under a simplified hull. Different cavity forms, a strong growth of the cavity length with the flow velocity and an optimal trim angle for the largest air-cavity area were identified. The results have shown that the computationally inexpensive three-dimensional potential-flow modelling can predict the air-cavity shapes and provide the qualitative agreement with the measured average length of the air cavity. There are several possibilities to change the surface of the ship's hull to reduce drag. The application of riblets, or sharkskin, is the most commonly accepted surface modification that leads to drag reduction. Riblets have been applied to commercial airliners in the form of an adhesive film, but the contamination of the riblets with dust and dirt rendered the riblets ineffective and too expensive for practical use. Recent findings suggest that wedges and dimples may obtain the same result. Other than riblets, the dimples would be larger and easier to maintain.