Fluidisation and plastic activity in a model soft-glassy material flowing in micro-channels with rough walls

TL;DR

This study uses mesoscopic simulations to explore how boundary roughness influences flow, fluidisation, and plastic activity in a soft-glassy material within micro-channels, revealing effects on slip, rheology, and plastic events.

Contribution

It demonstrates that boundary roughness reduces wall slip and promotes fluidisation, providing new insights into the interplay between roughness and plastic activity in soft-glassy flows.

Findings

Roughness reduces wall slip caused by wettability.

Roughness increases the rate of plastic events.

Flow scaling varies with distance from rough walls.

Abstract

By means of mesoscopic numerical simulations of a model soft-glassy material, we investigate the role of boundary roughness on the flow behaviour of the material, probing the bulk/wall and global/local rheologies. We show that the roughness reduces the wall slip induced by wettability properties and acts as a source of fluidisation for the material. A direct inspection of the plastic events suggests that their rate of occurrence grows with the fluidity field, reconciling our simulations with kinetic elasto-plastic descriptions of jammed materials. Notwithstanding, we observe qualitative and quantitative differences in the scaling, depending on the distance from the rough wall and on the imposed shear. The impact of roughness on the orientational statistics is also studied.