Morphology of anisotropic chains in a magneto-rheological fluid during aggregation and disaggregation processes

TL;DR

This study investigates the morphology and fractal properties of chain-like aggregates in magneto-rheological fluids under magnetic fields, revealing how external parameters influence aggregate conformation during formation and disassembly.

Contribution

It introduces a detailed analysis of aggregate morphology using fractal dimensions during magnetic field-induced aggregation and disaggregation, highlighting the dependence on field strength and particle concentration.

Findings

Box-counting dimension depends on the ratio R1/R0.

Family-Vicsek scaling function is verified during initial disaggregation.

Aggregate morphology varies with magnetic field and particle concentration.

Abstract

We study the morphology of the chain-like aggregates formed when a external constant and uniaxial magnetic field is applied to a magneto-rheological (MR) fluid. In order to characterize the conformation of the aggregates, we study the evolution of various fractal dimensions during aggregation and disaggregation processes (i.e., when the applied field is switched on and off), using video-microscopy and image analysis. Experiments have been performed by varying the values of two external parameters: the magnetic field amplitude and particle concentration. We found that the box-counting dimension, related with how the aggregates occupy the surrounding space, depends on the ratio $R_1/R_0$. During the first stage of the disaggregation process, when the particles are moving by Brownian motion inside the aggregate, Family-Vicsek scaling function is verified.