Dynamics of microstructure anisotropy and rheology of soft jammed suspensions

TL;DR

This paper investigates how microstructure anisotropy influences the rheological behavior of soft jammed suspensions, revealing complex transient phenomena and stress responses through a constitutive model based on particle-level dynamics.

Contribution

It introduces a novel constitutive model linking microstructure anisotropy to rheology, capturing transient effects and stress behaviors in soft jammed suspensions.

Findings

Microstructure anisotropy orientation affects yielding and flow.

Normal stress differences influence yield criteria and Trouton ratio.

Model explains stress overshoots, residual stresses, and modulus collapse.

Abstract

We explore the rheology predicted by a recently proposed constitutive model for jammed suspensions of soft elastic particles derived from particle-level dynamics [Cuny et al., Phys. Rev. Lett. 127, 218003 (2021)]. Our model predicts that the orientation of the anisotropy of the microstructure, governed by an interplay between advection and contact elasticity, plays a key role at yielding and in flow. It generates normal stress differences contributing significantly to the yield criterion and Trouton ratio. It gives rise to non-trivial transients such as stress overshoots in step increases of shear rate, residual stresses after flow cessation and power-law decay of the shear rate in creep. Finally, it explains the collapse of storage modulus as measured in parallel superposition for a yielded suspension.