Signatures of elastoviscous buckling in the dilute rheology of stiff polymers

TL;DR

This paper investigates how elastoviscous buckling in stiff polymers under shear flow affects their rheological behavior, revealing enhanced shear thinning and normal stress differences through numerical simulations.

Contribution

It uncovers the effects of elastoviscous buckling on dilute polymer suspension rheology, highlighting deviations from classic scaling laws at high flow strengths.

Findings

Enhanced shear thinning observed above buckling threshold

Increase in normal stress differences due to buckling

Signatures of elastoviscous buckling in rheological measurements

Abstract

As a stiff polymer tumbles in shear flow, it experiences compressive viscous forces that can cause it to buckle and undergo a sequence of morphological transitions with increasing flow strength. We use numerical simulations to uncover the effects of these transitions on the steady shear rheology of a dilute suspension of stiff polymers. Our results agree with classic scalings for Brownian rods in relatively weak flows but depart from them above the buckling threshold. Signatures of elastoviscous buckling include enhanced shear thinning and an increase in the magnitude of normal stress differences. We discuss our findings in the light of past work on rigid Brownian rods and non-Brownian elastic fibers and highlight the subtle role of thermal fluctuations in triggering instabilities.