Study about the structure and dynamics of magnetic nanofluids using a mesoscopic simulation approach

Abstract

In this paper, a new three-dimensional modeling of magnetic nanofluids based on a mesoscopic simulation approach is developed to study the aggregate structure of magnetic nanoparticles in equilibrium. The effect of the solvent is considered explicitly in the present model. The dynamics of a single magnetic nanoparticle is studied in detail. Magnetic nanoparticles are subjected to magnetic dipolar interaction force, steric force and the force exerted by dissipative particles described through the known Lennard-Jones potential, which make them experience translational motion. The corresponding rotational motion is also taken into account, which is caused by magnetic dipolar interaction and applied external magnetic field. The role of the solvent is embodied by using dissipative particles, whose introduction through the above-mentioned mesoscopic method makes the presented model approach the real magnetic nanofluids. This paper displays various structures of magnetic nanoparticles under different physical conditions. The obtained results are supported by experimental and numerical results in the literature. In particular, in the absence/presence of external field, chain structures are formed but their formation mechanisms and features are different, and the reason is analyzed in detail. In addition, there are rings and dense globes formed in the absence of magnetic field. Such study is very meaningful for understanding the macroscopic properties of magnetic nanofluids and extending the applications in biomedical and engineering fields.