Dr Richard Clarke, Associate Dean Post Graduate Research, Engineering department from the University of Auckland
Description
Date & Time: Friday, 24th August, 4pm
Venue: Ramanujan Hall
Speaker: Dr Richard Clarke, Associate Dean Post Graduate Research,
Engineering department from the University of Auckland
Title: Active Matter: A smart material for the 21st Century
Abstract: The theories of fluid dynamics and solid mechanics are a
cornerstone of Engineering, enabling us to make predictions about the way
in which materials and structures behave. The continuum-level mathematical
formulations which were developed over a century ago allow us to overcome
the impracticalities of considering every microscopic particle within the
system, and instead consider the material’s macroscopic bulk behaviour. The
type of substances usually described in this way are passive, meaning that
the drivers of the system are usually externally-applied forces or energy.
However, there exist more exotic types of active matter, where the
constituent components themselves contain a source of energy. Suspensions
of swimming microbes provide an important example. The innumerable cells
within the mixture are capable of self-propelling themselves through the
suspending medium. Modern micro- and nano-fabrication methods also allow
for the creation of artificial microswimmers. The flows generated by
self-motile cells leads to fluid-mediated coupling between the swimmers,
which can lead to highly-organised collective bulk motions, sometimes
referred to as bacterial turbulence or slow turbulence. This
self-organisation has also be seen to change the bulk rheology of the
suspension, leading to plastic and superfluidic behaviours, some of which
may have technological applications. Continuum models developed for passive
materials do not perform well for active matter, and so there has been a
great deal of interest and interdisciplinary activity in recent years to
derive an effective continuum-level description for such systems. In this
talk I will outline some of the current challenges, as well as ideas and
progress made to-date in this area.