Poiseuille flow of soft glasses in narrow channels: From quiescence to steady state

TL;DR

This study uses numerical simulations to explore how soft glasses transition from quiescence to steady Poiseuille flow in narrow channels, revealing stress-dependent fluidization and history effects.

Contribution

It uncovers the dynamics of flow onset, fluidization, and creep in confined soft glasses, highlighting the influence of initial conditions and local stresses.

Findings

Flow onset time increases with decreasing forcing

Rapid fluidization occurs via simultaneous local stress relaxation

Creep persists even when local stress exceeds the yield threshold

Abstract

Using numerical simulations, the onset of Poiseuille flow in a confined soft glass is investigated. Starting from the quiescent state, steady flow sets in at a time scale which increases with a decrease in applied forcing. At this onset time scale, a rapid transition occurs via the simultaneous fluidization of regions having different local stresses. In the absence of steady flow at long times, creep is observed even in regions where the local stress is larger than the bulk yielding threshold. Finally, we show that the time scale to attain steady flow depends strongly on the history of the initial state.