Spinning rods, microfluidics, and propulsion by cilia in biological systems

Roberto Camassa
University of North Carolina

An important component in understanding and modeling how human lungs function
lies in the hydrodynamics of the mucus fluid layers that coat lung airways.
In healthy subjects, the beating of cilia is thought to be the primary
mechanism for moving mucus. With the aim of establishing a quantitative
benchmark of how cilia motion propels the surrounding fluid,
we study the idealized situation of a single rod spinning in a fluid
obeying the Stokes approximation, the appropriate
limit for a Newtonian fluid with typical dimensions and time scales of cilia dynamics.
New approximate -- for cylindrical rods pinned to
a flat plane boundary, and exact -- for ellipsoidal rods freely spinning
around their center -- solutions for the fluid motion will be presented and compared
with the experimental data collected with spinning magnetic nano-rods in water.
In order to assess the influence of Brownian perturbations in this micro-scale experiment,
data from an experimental set-up scaled by dynamical similarity to
macroscopic (table-top) dimensions will also be presented and compared to the
theoretical predictions.

Audio (MP3 File, Podcast Ready)

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