Discoveries

April 10, 2024

Speed Racer

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Shark skin has captivated both fishermen and scientists in how it enables the marine predators to achieve astonishing speeds underwater.

Packed with small, anvil-shaped structures known as denticles, some species can swim at speeds topping 43 miles per hour – far outpacing Olympic swimmers who might reach a little more than three miles per hour.

While it’s widely believed that these denticles play a crucial role in shark locomotion by reducing drag, understanding their exact function has remained a challenge until now, Discovery Magazine reported.

In a new study, researchers from the University of Mississippi explained that shark skin not only decreases drag but also generates thrust in the direction of motion.

The research team conducted a series of experiments by simulating fluid flow over denticles similar in shape to those found on sharks.

Their simulations reveal that these denticles, arranged in a specific manner, create a secondary surface that alters the flow of fluid. This reverse flow generates thrust in the direction of movement by pushing against pillars that support the small anvil heads.

Termed “reverse pore thrust,” this phenomenon simultaneously aids in keeping the boundary layer attached to the surface, thereby reducing drag – which is crucial for efficient movement through water.

Their findings build on decades of research into the hydrodynamic properties of shark skin. Previous attempts to replicate this behavior have shown some success, with ridges aligned with the flow direction reducing drag by up to 10 percent.

The new study offers promising applications in engineering fields such as developing new designs to reduce drag in submarines and yachts.

Still, challenges remain, particularly in keeping synthetic shark skin free from marine fouling.

This story originally appeared in the April 10, 2024 newsletter, The Third Wheel.