  We use mesoscale simulations to gain insight into the digestion of
biopolymers by studying the break-up dynamics of polymer aggregates (boluses)
bound by physical cross-links. We investigate aggregate evolution, establishing
that the linking bead fraction and the interaction energy are the main
parameters controlling stability with respect to diffusion. We show
$\textit{via}$ a simplified model that chemical breakdown of the constituent
molecules causes aggregates that would otherwise be stable to disperse. We
further investigate breakdown of biopolymer aggregates in the presence of fluid
flow. Shear flow in the absence of chemical breakdown induces three different
regimes depending on the flow Weissenberg number ($Wi$). i) At $Wi \ll 1$,
shear flow has a negligible effect on the aggregates. ii) At $Wi \sim 1$, the
aggregates behave approximately as solid bodies and move and rotate with the
flow. iii) At $Wi \gg 1$, the energy input due to shear overcomes the
attractive cross-linking interactions and the boluses are broken up. Finally,
we study bolus evolution under the combined action of shear flow and chemical
breakdown, demonstrating a synergistic effect between the two at high reaction
rates.
