Rheology of dense fiber suspensions: Origin of yield stress, shear thinning and normal stress differences

TL;DR

This paper investigates the rheological behavior of dense rigid fiber suspensions, revealing that attractive interactions cause yield stress and shear-thinning, with a computational model that aligns well with experimental data.

Contribution

The study introduces a computational model that explains the origins of yield stress, shear-thinning, and normal stress differences in fiber suspensions, emphasizing the role of attractive interactions.

Findings

Attractive interactions induce yield stress in fiber suspensions.

The model accurately predicts shear-thinning viscosity.

Normal stress differences are also quantitatively captured.

Abstract

We explain the origins of yield stress, shear-thinning, and normal stress differences in rigid fiber suspensions. We investigate the interplay between the hydrodynamic, colloidal attractive and repulsive, and inter-fiber contact interactions. The shear-thinning viscosity and finite yield stress obtained from the computational model are in quantitative agreement with experiential results from the literature. In this study, we show that attractive interactions result in yield stress and shear-thinning rheology in the suspensions of rigid fibers. This is an important finding, given the ongoing discussion regarding the origin of the yield stress for suspensions of fibers. The ability of the proposed model to quantitatively predict the rheology is not limited to only shear thinning and yield stress but also extends to normal stresses.