Published: Feb. 14, 2020

Laura Miller, Department of Biology, University of North Carolina - Chapel Hill

Flow through the hairy appendages of small animals: The leaky rake to solid plate transition.

Numerous small organisms that swim, fly, smell, or feed in flows at the mesoscale, where inertial and viscous forces are balanced, use branched, bristled and hairy structures. Such mesoscale structures can augment underlying biological function (e.g., particle capture) by moving in a manner that transitions from acting as solid surfaces to leaky at Reynolds number close to one. Although mesoscale flows have been studied in many organisms, the fluid dynamic mechanisms underlying the leaky rake to solid plate transition remain unclear, and robust mathematical models are unavailable. I will present results from numerical simulations and experiments that demonstrate how these transitions affect locomotion, feeding, and exchange. Examples will include filtering flows through upside down jellyfish oral arms, airflows through bristled insect wings, exchange flows through corals, and sampling flows in crabs. In particular, the immersed boundary method will be used to resolve the flow through moving, flexible and porous structures.