Anisotropy of acoustic properties of magnetized magnetic fluids with ellipsoidal aggregates

TL;DR

This paper presents a model for sound propagation in magnetized magnetic fluids with ellipsoidal aggregates, linking aggregate geometry to acoustic properties and enabling non-contact analysis of aggregate sizes and growth.

Contribution

A novel quantitative model describing acoustic anisotropy in magnetic fluids with ellipsoidal aggregates, incorporating dipole interactions and matching experimental data.

Findings

Model accurately predicts attenuation and sound velocity.

Expressions reduce to classical forms in limiting cases.

Enables non-contact determination of aggregate sizes.

Abstract

A model of sound propagation in a magnetized magnetic fluid containing ellipsoidal aggregates is proposed. The model quantitatively describes the geometry of the aggregates formed from nanoparticles. Expressions for the attenuation coefficient and the sound velocity have been derived, taking into account dipole-dipole interaction between the aggregates. The model demonstrates good agreement with the experimental data. In limiting cases, the derived expressions reduce to classical ones, and the fitting parameters are merely geometric characteristics of the aggregates. The developed model enables the determination of aggregate sizes and the distances between them from an experiment that can be conducted without direct contact. The results obtained can also be used to analyze the field dependencies of acoustic properties and to model the kinetics of aggregate growth in a magnetic field.