<p style="text-align: justify">In the present study we have attempted to investigate a feasibility of exhibiting a significant trapping performance by means of multi-pairs of magnetic poles. Although we attempted various arrangements of multi-pairs of magnetic poles in a preliminary study, we here focus on the two representative types of configurations using two pairs of magnetic poles. That is, the first is a vertical configuration of two pairs of magnetic poles, where each pair of magnetic poles is arranged perpendicular to the flow direction, and the second is a parallel configuration, where each pair of magnetic poles is arranged along the wall surface of a circular cylinder. As in the previous study for one pair of magnetic poles, we have here investigated the behavior of magnetic rod-like particles in a Hagen-Poiseuille flow, by means of Brownian dynamics, in the above-mentioned of two pairs of magnetic poles, which induce magnetic forces to function to trap magnetic particles around the magnetic poles. In the case of the vertical arrangement of the two pairs of magnetic poles, a largely-packed aggregate is trapped between the first pair of magnetic poles, and this trapping characteristic is reproduced between the second pair of magnetic poles. In this case, these large clusters are mainly formed in the center area of the cylinder perpendicular to the flow direction. Since the flow in the center area is quite fast in comparison with the flow in the wall surface area, it is difficult to trap these large clusters around magnetic poles. That is, largely-packed clusters are separated from the anchored particles and flow away in the downstream direction along the centerline area of the cylinder. In contrast, for the case of the parallel arrangement, a largely-packed cluster is formed between a pair of magnetic poles and located along the wall surface. Different from the previous arrangement of magnetic poles, this largely-packed cluster may sufficiently survive and be trapped between the poles by shifting the position nearer to the wall surface. If the magnetic particle-particle interaction is relatively more dominant than the magnetic particle-field interaction, magnetic rod-like particles are trapped at the wall surface to form an arch-type cluster between a pair of magnetic poles. In contrast, if the magnetic particle-particle interaction is a significant governing factor, magnetic particles aggregate to form spherical clusters in the centerline area and singly flow away in the downstream direction without being trapped. In the present paper, the influence of the magnetic particle-particle interaction strength, the applied magnetic field strength, the separation distance between a pair of magnetic poles, etc., on the trapping characteristics has been addressed and discussed in detail. From these results and discussion, we understand that appropriate conditions of the above-mentioned factors give rise to a better trapping performance in the parallel arrangement of magnetic poles.</p>

Trapping Characteristics of Magnetic Rod-Like Particles via Multi-Magnetic Poles in a Hagen-Poiseuille Flow (Brownian Dynamics Simulations)

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

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