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MIT's Beaver-Inspired Wetsuits

takyon and Phoenix666 write in with the same story:

MIT researchers are designing wetsuits that use the same mechanism that keeps beavers and sea otters warm when diving:

Beavers and sea otters lack the thick layer of blubber that insulates walruses and whales. And yet these small, semiaquatic mammals can keep warm and even dry while diving, by trapping warm pockets of air in dense layers of fur. Inspired by these fuzzy swimmers, MIT engineers have now fabricated fur-like, rubbery pelts and used them to identify a mechanism by which air is trapped between individual hairs when the pelts are plunged into liquid.

The results, published in the journal Physical Review Fluids, provide a detailed mechanical understanding for how mammals such as beavers insulate themselves while diving underwater. The findings may also serve as a guide for designing bioinspired materials — most notably, warm, furry wetsuits. "We are particularly interested in wetsuits for surfing, where the athlete moves frequently between air and water environments," says Anette (Peko) Hosoi, a professor of mechanical engineering and associate head of the department at MIT. "We can control the length, spacing, and arrangement of hairs, which allows us to design textures to match certain dive speeds and maximize the wetsuit's dry region."

Air entrainment in hairy surfaces (DOI: 10.1103/PhysRevFluids.1.033905) (DX)

Motivated by diving semiaquatic mammals, we investigate the mechanism of dynamic air entrainment in hairy surfaces submerged in liquid. Hairy surfaces are cast out of polydimethylsiloxane elastomer and plunged into a fluid bath at different velocities. Experimentally, we find that the amount of air entrained is greater than what is expected for smooth surfaces. Theoretically, we show that the hairy surface can be considered as a porous medium and we describe the air entrainment via a competition between the hydrostatic forcing and the viscous resistance in the pores. A phase diagram that includes data from our experiments and biological data from diving semiaquatic mammals is included to place the model system in a biological context and predict the regime for which the animal is protected by a plastron of air.

Also reported here.

Original Submission #1  Original Submission #2