Speaker
Joakim Stenhammar
(Lund University)
Description
"Active matter" is usually defined as materials that are
driven out of thermodynamic equilibrium at the microscopic
scale, usually by the persistent conversion of chemical fuel
into motion. Such materials are often characterized as
either "dry", dominated by frictional damping, or "wet",
dominated by interactions mediated by a momentum-conserving
solvent. Because of their strong deviation from equilibrium,
these two classes of active matter exhibit very different,
although equally intriguing, collective behaviours. In this
talk, I will analyze two such classes of collective
behaviours occuring in simple model systems of active
matter, namely 1) "motility-induced phase separation",
whereby active particles that interact solely through
excluded volume interactions undergo a separation into dense
and dilute phases, and 2) "bacterial turbulence", the
hydrodynamically mediated transition into a coherently
flowing state observed in dipolar microswimmers such as
swimming bacteria.