Speaker
Antti Puisto
(Aalto University, Helsinki, Finland)
Description
Aqueous foams are an important model system that displays
coarsening dynamics. Coarsening in dispersions and foams is
well understood in the dilute and dry limits, where the gas
fraction tends to zero and one, respectively. However, foams
are known to undergo a jamming transition from a fluid-like
to a solid-like state at an intermediate gas fraction,
$\phi_c$. Much less is known about coarsening dynamics in
wet foams near jamming, and the link to mechanical response,
if any, remains poorly understood. In this talk, we discuss
coarsening and mechanical response using numerical
simulations of a mesoscale model for wet foams. As in other
coarsening systems we find a steady state scaling regime
with an associated particle size distribution. We relate the
time-rate of evolution of the coarsening process to the
wetness of the foam and identify a characteristic coarsening
time that diverges approaching jamming. In addition, we
probe the mechanical response of the system to strain while
undergoing coarsening. We find two competing time scales,
namely the coarsening time and the mechanical relaxation
time. We relate these to the evolution of the elastic
response and the mechanical structure.
