Hydrodynamics substantially affects induced structure formation in magnetic fluids

TL;DR

This paper reveals that hydrodynamic interactions significantly influence the formation of structures in magnetic fluids under magnetic fields, promoting the development of slender chains over compact clusters.

Contribution

It demonstrates the crucial role of hydrodynamic interactions in structure formation within magnetorheological fluids, a factor previously underappreciated.

Findings

Hydrodynamic interactions support the formation of slender chains.

Absence of hydrodynamic interactions leads to more compact clusters.

Hydrodynamics substantially influence the structuring process.

Abstract

Magnetorheological fluids consist of micrometer-sized magnetic particles in a carrier liquid. Sufficiently strong external magnetic fields lead to the formation of string-like particle aggregates. We demonstrate that hydrodynamic interactions, that is, mutual couplings via induced flows, play a substantial role during the structuring process. They support the formation of slender chains instead of more compact clusters in the absence of mutual hydrodynamic interactions between the particles. This fundamental insight is substantial from an application perspective, due to the enormous technical importance and potential of structured magnetorheological materials.