Fluid Power and Handling

FILTRATION FILCHES FROM FILTER FEEDERS

For decades, engineers have been taking cues from nature to design better products and devices. Now, engineers at the Massachusetts Institute of Technology have discovered that industrial filtration systems—used to remove everything from airborne particles to viruses from flowing air or liquids—could be improved by adopting designs from marine animals that pull food out of water.

Specifically, Anette “Peko” Hosoi, the Pappalardo Professor of Mechanical Engineering at MIT, and her team looked at the filter-feeding mechanism of mobula rays, which feed by swimming open-mouthed through plankton-rich regions of the ocean and filtering plankton particles into their gullet as water streams into their mouths and out through their gills. Parallel comb-like structures, called plates, within a ray’s mouth siphon water into the gills. The structure of the plates enables food particles to skip across the plates and deeper into the mouth.

The researchers realized that the ray’s filtering features act like industrial cross-flow filters, which allow most of the fluid to pass through while contaminants flow across the membrane and into a pollution-capture system. In the case of the grooved filter of the mobula ray, the researchers discovered that at a certain fluid speed, tiny vortices formed at the mouth of the groove; water flowed through the vortices but particles did not. The researchers said the insight will help them design more effective industrial filters.