Dumbbells in suspension: A numerical study on their dynamics and shear viscosity

TL;DR

This study uses fluid particle dynamics simulations to explore how elastic dumbbells affect shear viscosity in dilute suspensions, revealing significant interaction effects at certain flow conditions.

Contribution

It provides new insights into the nonlinear effects of dumbbell interactions on shear viscosity, especially at larger mean lengths and specific flow regimes.

Findings

Single dumbbells increase shear viscosity via boundary stress.

Interacting dumbbells significantly raise viscosity beyond unconnected beads.

Effects are prominent at larger mean dumbbell lengths and low Weissenberg numbers.

Abstract

The dynamics of elastic dumbbells in linear shear flow is investigated by fluid particle dynamics simulations at small Reynolds numbers. The positive contribution of a single dumbbell to the effective shear viscosity is determined via the extra stress exerted at the boundaries of the shear cell and the difference to the contributions obtained via the Kramers-Kirkwood formula are described. For a small Weissenberg number and when the mean dumbbell length becomes larger than the mean next-neighbor distance, the contribution of interacting dumbbells to the mean shear viscosity exceeds significantly the contribution of unconnected beads occupying the same volume fraction.