Signatures of elastoviscous buckling in the dilute rheology of stiff polymers

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 fibres and highlight the subtle role of thermal fluctuations in triggering instabilities.

Automated summary

Numerical simulations are used to uncover the effects of morphological transitions on the steady shear rheology of a dilute suspension of stiff polymers as they tumble in shear flow. The results are in agreement with classic scalings for Brownian rods in relatively weak flows but differ above the buckling threshold, showing enhanced shear thinning and an increase in normal stress differences. The study highlights the subtle role of thermal fluctuations in triggering instabilities, based on past work on rigid Brownian rods and non-Brownian elastic fibers.