Dynamics of microstructure anisotropy and rheology of soft jammed suspensions.

Cuny, Nicolas; Bertin, Eric; Mari, Romain · Soft Matter · 2022

basic_science · Level V

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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 <i>et al.</i>, <i>Phys. Rev. Lett.</i>, 2021, <b>127</b>, 218003]. 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.