Brownian dynamics simulation of a dispersion composed of disk-like hematite particles regarding aggregation phenomena

Satoh, Akira

doi:10.1016/j.colsurfa.2015.07.047

Cited by 14 publications

(17 citation statements)

References 31 publications

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“…A disk-like particle, which has a cross section of spherocylinder when the particle is cut by a plane through the particle axis, is used as a model for oblate hematite particles, as in the previous study [47]. That is, this disk-like particle has a cylindrical inner part with diameter d and a torus part covering the cylinder with the cross section of a half circle: the diameter and the thickness of the particle are denoted by d 1 and b 1 , respectively, and the aspect ratio r p is defined as r p =d 1 /b 1 .…”

Section: Particle Modelmentioning

confidence: 99%

“…The force F ij (m) and torque T ij (m) act on particle i by particle j due to the magnetic interaction between the particles. Moreover, as in the previous study [47], the magnetic particle is assumed to be coated with a uniform steric (or surfactant) layer with thickness δ. The force F ij (V) and torque T ij (V) act on particle i by particle j due to the overlap of these steric layers.…”

Section: Particle Modelmentioning

confidence: 99%

“…The previous study focuses on analysis of aggregate structures in a suspension composed of disk-like hematite particles subject to various conditions [47]. In the present study, we address the disk-like hematite particle suspension as in the previous work, but we investigate the orientational characteristics and magneto-rheological effect in a simple shear flow by means of Brownian dynamics simulations.…”

Section: Introductionmentioning

confidence: 97%

“…Furthermore, Brownian dynamics simulations with magnetic interactions between particles have clarified the influence of the aggregate structures on the orientational characteristics and negative magneto-rheological effect [43,44], which are quite difficult to analyze solely by the theory based on the orientational distribution function. Currently, these theoretical and simulation approaches have been applied to the study on a suspension composed of oblate hematite particles [47].…”

Section: Introductionmentioning

confidence: 99%

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Brownian dynamics simulation of a dispersion composed of disk-like hematite particles regarding the orientational distribution and the magneto-rheological properties

Satoh

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Section: Particle Modelmentioning

confidence: 99%

Section: Particle Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Brownian dynamics simulation of a dispersion composed of disk-like hematite particles regarding the orientational distribution and the magneto-rheological properties

Satoh

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…粒子の回転運動の方程式より，磁気モーメントの方向 e を与える式が次のように得られる (Satoh, 2015a(Satoh, , 2015b (Satoh, 2015a(Satoh, , 2015b Fig. 6 Dependence of the heating effect on the magnetic particle-particle interaction strength.…”

Section: 緒言unclassified

Aggregation phenomena of a magnetic particle suspension in an alternating magnetic field and the influence on the heat generation effect (Brownian dynamics simulations)

Suzuki

Satoh

Futamura

2018

Transactions of the JSME (In Japanese)

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We have elucidated the aggregation phenomena in a suspension composed of spherical magnetic particles in an alternating magnetic field by means of Brownian dynamics method. The relationship between aggregate structures and heating phenomena has been discussed using the hysteresis loops of the magnetic field-magnetization curves, which were obtained from Brownian dynamics simulations. A large heating effect is inevitably necessary in applying a magnetic particle suspension to magnetic hyperthermia treatment in the medical engineering field. We here focus on the Brownian relaxation mode of magnetic moments of particles as the factor inducing the heating effect. The main results obtained here are summarized as follows. In the situation where stable chain-like clusters are formed in the field direction, the magnetic particle-particle interaction induces a significant delay for the magnetic moments inclining in the alternating magnetic field direction. These chain-like clusters respond to a change in the magnetic field without collapse and reformation of the clusters, by the magnetic moment of each constituent particle rotating to incline in the field direction. These behaviors of chain-like clusters in an alternating magnetic field exhibit a hysteresis loop with large area in the magnetic filed-magnetization curve, which gives rise to a significantly large heating effect. On the other hand, in the situation where large clusters are formed but these clusters do not strongly tend to incline in the field direction, the area of the hysteresis loop becomes small and therefore a large heating effect cannot be obtained.

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Utilizing yield‐stress fluids to suppress chaining during magnetic alignment of microdisks via rotating fields

et al. 2018

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Inkjet printing can be used to deposit photopolymerizable magnetic inks for the creation of functionalized composites. Anisotropic properties in the composites can be achieved when inkjet printing is combined with external magnetic fields to align magnetically orientable particles (MOPs). When a MOP is induced by an external magnetic field, it will create its own magnetic field that can attract neighboring particles. The coarsening of particles into higher-order structures like chains and sheets is unwanted in certain areas, such as high-frequency applications. We show that this particleparticle attraction and subsequent particle migration can be inhibited with the introduction of a yield stress into the suspending medium, while still allowing the alignment of the particle to proceed. For magnetically induced rotational and translational motions for oblate spheroids in a rotating magnetic field, theoretical scalings are presented for the characteristic timescales in a linear fluid and for the characteristic stresses in a yield-stress fluid. Figure 2. Geometric arrangements of chaining events. The magnetic field rotates in the (xy)-plane.(a) Two oblate spheroids with induced dipoles. (b) Sheets formed by a rotating magnetic field that are taken from experiments. The dimensions of the particles are approximately a=2:5 μm and c=75 nm, and the volume fraction is ϕ=0.001. Eight sheets are identified with a sheet spacing of d exp =80AE37 μm. (c) Ideal hexagonal sheet formation under a rotating magnetic field. A unit cell is chosen in the blue rhombus. [Color figure can be viewed at wileyonlinelibrary.com]Figure 3. Yield stress as a function of concentration of gellan gum.(a) Bulk rheological results for concentration of gellan gum from 0.001 to 0.1% in 1% NaCl. The triangle (4) indicates the value for the microscopic yield stress that was calculated from the sedimentation suppression. The asterisks (*) indicate the values of the microscopic yield stress that was obtained from pulling active microrheology. (b)-(c) Timelapse sedimentation experiment. PS particles with magnetic inclusions (d=4:3 μm, ρ=1:22�0:02 g/cm 3 ) were injected into various concentrations of gellan gum (CG-HA). From left to right, C GG = {0.0100, 0.0150, 0.0200, 0.0225, 0.0250, 0.0300, 0.0400, 0.0500}% in C NaCl =1% (note that concentrations in the photos are shown as weight per volume percent times 10 4 ). Values from the microscopic rheological results are included. (b) Suspensions immediately after they were vortexed for 30 s for particle suspension. (c) Complete sedimentation of PS particles with magnetic inclusions occurs after 24 h for all concentrations below 0.02%. Concentrations above 0.025% were able to suspend particles indefinitely.[Color figure can be viewed at wileyonlinelibrary.com] Figure 5. Directed alignment of Ni-Fe microdisks (360 lm diameter) in 0.065% gellan gum.Field strength was increased sequentially from 0 to 7 mT. The magnetic field rotates in the (x, y)-plane. Particles that are aligned in the (x, y)-plane appear circular...

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Brownian dynamics simulation of a dispersion composed of disk-like hematite particles regarding aggregation phenomena

Cited by 14 publications

References 31 publications

Brownian dynamics simulation of a dispersion composed of disk-like hematite particles regarding the orientational distribution and the magneto-rheological properties

Brownian dynamics simulation of a dispersion composed of disk-like hematite particles regarding the orientational distribution and the magneto-rheological properties

Aggregation phenomena of a magnetic particle suspension in an alternating magnetic field and the influence on the heat generation effect (Brownian dynamics simulations)

Utilizing yield‐stress fluids to suppress chaining during magnetic alignment of microdisks via rotating fields

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