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The inner nanostructure of the dispersing particles plays a key role in determining the magnetorheological properties of the magnetic fluids. In this work, a particle-level dynamic simulation is conducted to study the rheological properties of magnetic liquids based on the anisotropic Fe₃O₄ nanospheres-assembled-nanochains. Both the slenderness ratio and diameter directly affect the dip Angle of the microstructure and the interaction force between particles indirectly contributes to the macroscopic shear stress. When the concentration is kept at 30 wt%, the Fe₃O₄ nanospheres-chains with a slenderness ratio of 7 and diameter of 20 nm show the best rheological properties. Under a larger slenderness ratio, the aggregation of the nanospheres-chains becomes serious which often leads to stronger interactions. As a result, due to change of inclination Angle and degree of aggregation, the shear stress is determined by both the slenderness ratio and diameter, and these simulation results qualitatively agree with the previous experimental results. In addition, a parallel computing is applied to maximize the computing power of the server which also save the computing time. This simulation provides detailed insight into the mechanism of the magnetorheological effect and shows high potential in designing high performance magnetorheological fluids.
 

magnetic fluid,MR effect,microstructures,particle-level dynamic simulations