Making Tags Less of a Drag: Optimising Biologging Devices with Computational Fluid Dynamics

Post provided by WILLIAM KAY

Drag and Biologging Devices

A harbour seal tagged with a biologging device. ©Dr Abbo van Neer

A harbour seal tagged with a biologging device. ©Dr Abbo van Neer

Michael Phelps is one of the most decorated Olympic athletes of all time and the world’s fastest swimmer. And yet, he could swim faster. Wearing the Speedo LZR Racer supersuit Michael Phelps could reduce his hydrodynamic drag, or water resistance, by upwards of 40%. That could increase his swim speed by more than 4%! In competition, that’s the difference between silver and gold. But, if Phelps forgot to remove his “drag socks” – cumbersome footwear designed to increase water resistance for strength training – his speed would be dramatically reduced. He’d be lucky to walk away with bronze!

Professional swimmers have adapted to the use of performance enhancing technologies to decrease their drag, but that’s nothing compared to the adaptations made by wild animals. Creatures in the marine environment have evolved incredible adaptations to decrease drag, such as extreme streamlining in marine mammals and seabirds. This allows them to move underwater as quickly and efficiently as possible. Seals, for example, are pretty ungainly on land, but in the water they’re sleek and rapid. They have a body shape designed to maximise speed while swimming.

When we study marine animals we often use tracking devices, which can be attached using harnesses, glue, or suction-cups. These ‘biologging devices‘, or tags, are similar to Fitbits. Attaching them to animals allows us to record, amongst other things, all of the animal’s movements and behaviours. This information is crucial to understanding their ecology and for improving their conservation management. Continue reading