Ultrasonic propagation: A technique to reveal field induced structures in magnetic nanofluids

•Ultrasonic propagation is used to reveal field induced structures in magnetic nanofluid.•Velocity anisotropy versus magnetic field shows double peak behavior in kerosene base fluid.•Transformer oil based fluid shows only positive saturating behavior with field.•Tarapov’s theory is used to analyze types of field induced structure formation.•Chain like structures forms in kerosene whereas fractals form in transformer oil based fluid.

The paper reports the study of magnetic field induced structures in magnetic nanofluid investigated through ultrasonic wave propagation. Modified Tarapov’s theory is used to study variation in velocity anisotropy with magnetic field. The types of field induced structures depend upon the chemical structure of the carrier in which magnetic nanoparticles are dispersed. Our study indicates formation of fractals and chain respectively, in transformer oil and kerosene based fluid. This difference is explained on the basis of particle–particle interaction and particle–medium interaction.