Simulation of the Chain-formation Process in Magnetic Fields

Abstract

The chain formation process of ferromagnetic particles under an applied magnetic field is simulated. Three main forces -magnetic force, viscous force, and repelling force, are considered. A model to simulate the motion of particles is proposed based on the analysis of the dynamics of the particles, and a corresponding numerical approach is developed. The formation of particle chains in magnetorheological (MR) fluids under an applied magnetic field is simulated, and the result agrees well with the experimental observation. The developed method is significant for the analysis of the overall behavior of MR fluids and their microscopic mechanisms as well as the effects of the influencing factors, which may be helpful for the design of new MR fluids.

Influence of magnetic field-aided filler orientation on structure and transport properties of ferrite filled composites

“…Each hard ferromagnetic grain is suspended in fluid with possibility of motion and rotation and can be considered as single domain [11]. Unlike the paramagnetic materials, the moment comes not only from polarization with the external field, but also form own remanence magnetization of the particle.…”

“…The four main forces are taken into account: gravity, buoyancy, viscous forces, as well as magnetic interactions with external field and between particles. For a given particle, the following equations should be fulfilled [11]:…”

“…The local field at particle i, induced by dipolar particle j (Fig. 11), can be determined as: [11] , [19] , [20]   …”

“…The force exerted on the particle i, due to local field generated by the particle j is expressed as: [11] , [20]       Total magnetic force acting on the particle can be derived from the formula:…”

“…Several papers can be found in the literature, which implement basic interactions in magnetorheological fluids. For example Li [11] presents the way of performing computer simulations on the arrangement of the structures under the influence of a magnetic field. Thanks to the simulations, the process of particles movement and estimation of the time in which the particles are ordered in chain-like structures can be depicted.…”