Mesoscale modelling of polymer aggregate digestion

TL;DR

This paper uses mesoscale simulations to understand how biopolymer aggregates break up during digestion, considering factors like cross-linking, chemical breakdown, and fluid flow effects.

Contribution

It introduces a mesoscale simulation approach to analyze biopolymer aggregate digestion, highlighting the roles of cross-linking, chemical breakdown, and shear flow regimes.

Findings

Linking bead fraction and interaction energy control aggregate stability.

Chemical breakdown disperses otherwise stable aggregates.

Shear flow induces different breakup regimes depending on Wi.

Abstract

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.