Researchers from Harvard University and the University of South Carolina have discovered that incorporating structures modelled on elements of sharks’ skin into the design of aerofoils can improve their performance by up to 323%.

The scientists focused on ‘denticles’, thousands of small scales of a variety of sizes and shapes found across the skin of many sharks in their study, ‘Sharkskin-inspired designs that improve aerodynamic performance’, published in the Journal of the Royal Society Interface.

To date there has been considerable study into the effects of denticles on drag. For example, ‘Drag Reduction by Riblets & Sharkskin Denticles: A Numerical Study’, published by the University of Minnesota in 2015, concluded that denticles can increase drag by between 44% and 50%.

However, in this latest study the team of evolutionary biologists and engineers led by August G. Domel investigated the effects of denticles on lift, the force responsible for elevating aircraft off the ground.

The team imaged the denticles of the shortfin mako, the world’s fastest shark, using micro-CT scanning. Then they 3D-printed denticle shapes on the suction side of an aerofoil, the curved top side that causes passing air particles to spread out, lowering the air pressure above the wing, and generating lift to drive the wing upwards.

By testing 20 different combinations of denticle sizes, rows and row positions, the researchers found that the sharkskin features did not only reduce drag, but increased lift. Domel claimed the denticles created a form of ‘shark-inspired vortex generators’, devices which typically consist of a vane and are attached to an aerofoil to increase lift.

The study goes on to name ‘streamwise vortices that replenish momentum loss in the boundary layer’ as another key reason for the greater efficiency.

“Our findings not only open new avenues for improved aerodynamic design,” concludes the report, “but also provide new perspective on the role of the complex and potentially multifunctional morphology of shark denticles for increased swimming efficiency.”