<p style="text-align: justify">In addition to typical application fields such as fluid engineering, magnetic particle suspensions are significantly potential as an application in the field of biomedical engineering such as magnetically-guided drug delivery and magnetic hyperthermia medical treatment. In these applications, it is required to investigate the dynamic and static behaviors of magnetic particles in a flow field in the situation of a time-dependent or a non-uniform applied magnetic field. In the flow analysis in these situations, it is desirable to take into account multi-body hydrodynamic interactions among dispersed magnetic particles, especially for a non-dilute particle system. In the present study, we have elucidated the feasibility of the multi-particle collision dynamics (MPCD) method as a technique for taking into account multi-body hydrodynamic interactions. Previous Monte Carlo and Brownian dynamics simulations by the present authors evidently showed that in certain situations of magnetic particle-particle and particle-field interaction strengths, magnetic disk-like particles significantly aggregate to form linear column-like clusters with neighboring particles in a cluster in a face-to-face contact configuration. This face-to-face contact gives rise to a significantly stable column-like cluster, even in a flow field situation, that makes significant influence on fluid characteristics such as the magnetorheological properties of a particle suspension. From this instance, we certainly understand that magnetic disk-like particles have a hopeful potentiality for the application to the above-mentioned biomedical engineering in addition to the traditional magnetically-controlled fluid devices. From this background, we here focus on the feasibility of the MPCD by addressing the activation level of the Brownian motion of magnetic disk-like particles because their internal structure is strongly dependent on particle Brownian motion. The random motion of virtual fluid particles is almost accurately activated, but in contrast, the translational and rotational Brownian motion of magnetic disk-like particles are slightly over-activated than the theoretical Brownian motion. However, the use of a sufficiently small time interval in simulations is able to give rise to a physically reasonable level of both the translational and rotational Brownian motion. Moreover, it is seen that the magnetization curves are in relatively good agreement with the Langevin derived curve, particularly in the range of larger magnetic fields. This characteristic is quite important for a suspension of magnetic disk-like particles, because in the situation of a strong applied magnetic field, stable long column-like clusters are formed in the system. We may conclude that the MPCD simulation method is able to reproduce physically reasonable macroscopic properties of a magnetic disk-like particle suspension and is sufficiently feasible as a particle-based simulation technique for investigating the dynamic properties of this particle suspension and also is able to take into account both particle Brownian motion and multi-body hydrodynamic interactions.</p>

Feasibility of the Multi-Particle Collision Dynamics Method for Taking Into Account Multi-Body Hydrodynamic Interactions (Magnetic Disk-Like Particle Suspension)

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

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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