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Influence of interparticle friction on the magneto-rheological effect for magnetic fluid: a simulation investigation

This work studied the effect of interparticle friction force on the magnetorheological properties for magnetic fluid using particle-level dynamic simulations. A novel numerical model considering the friction force and elastic normal force between coarse microspheres was developed. The analysis revealed the relationship between magnetic fluid microstructure and friction coefficient (μ) of particles for the first time. Under steady shear flow, plate-like aggregations were formed under a moderate friction coefficient (μ≈ 0.2), while thick chains with large inclinations were observed under strong friction forces (μ > 1.5). When 0.2 ≤ μ ≤ 1.5, the friction forces hardly affected the rheological properties. If μ > 1.5, friction forces could enhance the shear stress by 102%. Friction force hampered the relative movement of magnetic particles in the thick chains and enlarged the average dip angle of microstructures. The magnetic dipolar force between microspheres generated stronger shear stress in such particle aggregations. The optimal friction coefficient was determined as 2 ≤ μ ≤ 2.75 in simulations by considering the saturation magnetizations, external fields, shear rates, and particle concentrations. The enhancement of shear stress was relevant to the relative strength between magnetic force and friction interaction. Simulated shear stress in magnetic field sweep matched well with experiments in the literature. This work will open a promising avenue in the development of high-performance magnetic fluid.