# Self-assembly and rheology of dipolar colloids in simple shear - studied by multi-particle collision dynamics

## TL;DR

This study uses advanced simulations to explore how dipolar colloids self-assemble under shear and how their microstructure influences rheological behavior, revealing universal structural dynamics across different systems.

## Contribution

It introduces a hybrid simulation approach combining molecular dynamics and multi-particle collision dynamics to quantify the microstructure-rheology relationship in dipolar colloids.

## Key findings

- Viscosity varies over several orders of magnitude.
- Universal structural behavior governed by bonding and erosive stresses.
- Quantitative agreement with literature data.

## Abstract

Magnetic nanoparticles in a colloidal solution self-assemble in various aligned structures, which has a profound influence on the flow behavior. However, the precise role of the microstructure in the development of the rheological response has not been reliably quantified. We investigate the self-assembly of dipolar colloids in simple shear using hybrid molecular dynamics and multi-particle collision dynamics simulations with explicit coarse-grained hydrodynamics; conduct simulated rheometric studies and apply micromechanical models to produce master curves, showing evidence of the universality of the structural behavior governed by the competition of the bonding (dipolar) and erosive (thermal and/or hydrodynamic) stresses. The simulations display viscosity changes across several orders of magnitude in fair quantitative agreement with various literature sources, substantiating the universality of the approach, which seems to apply generally across vastly different length scales and a broad range of physical systems.