Particle Actuation by Rotating Magnetic Fields in Microchannels: A Numerical Study

Soft Matter ◽  
2021 ◽  
Author(s):  
Seokgyun Ham ◽  
Wen-Zhen Fang ◽  
Rui Qiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Numerical Study ◽  
Rotating Magnetic Field ◽  
Rotating Magnetic Fields ◽  
Translation Motion

Magnetic particles confined in microchannels can be actuated to perform translation motion using a rotating magnetic field, but their actuation in such a situation is not yet well understood. Here,...

Frequency-dependent conversion of the torque of a rotating magnetic field on a ferrofluid confined in a spherical cavity

Soft Matter ◽  
2019 ◽  
Vol 15 (44) ◽  
pp. 9018-9030
Author(s):  
Klaus D. Usadel ◽  
Anastasiya Storozhenko ◽  
Igor Arefyev ◽  
Hajnalka Nádasi ◽  
Torsten Trittel ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
Magnetic Fields ◽  
Spherical Cavity ◽  
Rotating Magnetic Field ◽  
Rotating Magnetic Fields ◽  
Frequency Dependent

The dynamics of magnetic nanoparticles in rotating magnetic fields is studied both experimentally and theoretically.

Control of the Macrosegregations during Solidification of a Binary Alloy by Means of a AC Magnetic Field

2006 ◽  
Vol 508 ◽  
pp. 163-168 ◽  
Author(s):  
Xiao Dong Wang ◽  
A. Ciobanas ◽  
Florin Baltaretu ◽  
Anne Marie Bianchi ◽  
Yves Fautrelle
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Mushy Zone ◽  
Binary Alloy ◽  
Solidification Front ◽  
Laminar Flows ◽  
Rotating Magnetic Field ◽  
Moderate Intensity ◽  
Mushy Region ◽  
Rotating Magnetic Fields

A numerical model aimed at simulating the segregations during the columnar solidification of a binary alloy is used to investigate the effects of a forced convection. Our objective is to study how the segregation characteristics in the mushy zone are influenced by laminar flows driven both by buoyancy and by AC fields of moderate intensity. Various types of magnetic fields have been tested, namely travelling, rotating magnetic field and slowly modulated electromagnetic forces. The calculations have been achieved on two types of alloys, namely tin-lead and aluminiumsilicon. It is shown that the flow configuration changes the segregation pattern. The change comes from the coupling between the liquid flow and the top of the mushy zone via the pressure distribution along the solidification front. The pressure difference along the front drives a mush flow, which transports the solute in the mushy region. Another interesting type of travelling magnetic field has been tested. It consists of a slowly modulated travelling magnetic field. It is shown that in a certain range of values of the modulation period, the channels are almost suppressed. The normal macrosegregation remains, but the averaged segregation in the mushy zone is weaker than in the natural convection case. The optimal period depends on the electromagnetic force strength as well as the cooling rate. The latter phenomenon cannot occur in the case of rotating magnetic fields, since in that configuration the sign of the pressure gradient along the solidification front remains unchanged. Recent solidification experiments with electromagnetic stirring confirm the predicted macrosegregation patterns.

Semiconductor Crystal Growth by the Vertical Bridgman Process With Transverse Rotating Magnetic Fields

2006 ◽  
Vol 129 (2) ◽  
pp. 241-243 ◽  
Author(s):  
X. Wang ◽  
N. Ma
Keyword(s):  
Magnetic Field ◽  
Crystal Growth ◽  
Magnetic Fields ◽  
Applied Magnetic Field ◽  
Rotating Magnetic Field ◽  
Semiconductor Crystal ◽  
Rotating Magnetic Fields ◽  
Electrically Conducting ◽  
Vertical Bridgman ◽  
Bridgman Process

During the vertical Bridgman process, a single semiconductor crystal is grown by the solidification of an initially molten semiconductor contained in an ampoule. The motion of the electrically conducting molten semiconductor can be controlled with an externally applied magnetic field. This paper treats the flow of a molten semiconductor and the dopant transport during the vertical Bridgman process with a periodic transverse or rotating magnetic field. The frequency of the externally applied magnetic field is sufficiently low that this field penetrates throughout the molten semiconductor. Dopant distributions in the crystal are presented.

Tuning mass transport in magnetic nanoparticle-filled viscoelastic hydrogels using low-frequency rotating magnetic fields

Soft Matter ◽  
2017 ◽  
Vol 13 (36) ◽  
pp. 6259-6269 ◽  
Author(s):  
Shahab Boroun ◽  
Faïçal Larachi
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Mass Transport ◽  
Magnetic Nanoparticle ◽  
Low Frequency ◽  
Rotating Magnetic Field ◽  
Rotating Magnetic Fields ◽  
Rotational Movement

Rotational movement of MNPs in ferrogels in an external rotating magnetic field for tuning mass transport.

scholarly journals Power and Momentum Relations in Rotating Magnetic Field Current Drive

1984 ◽  
Vol 37 (5) ◽  
pp. 509 ◽  
Author(s):  
WN Hugrass
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
Phase Velocity ◽  
Current Drive ◽  
Rotating Magnetic Field ◽  
Plasma Current ◽  
Rotating Magnetic Fields ◽  
Frequency Source ◽  
Rotating Field

The use of rotating magnetic fields (RMF) to drive steady currents in plasmas involves a transfer of energy and angular momentum from the radio frequency source feeding the rotating field coils to the plasma. The. power-torque relationships in RMF systems are discussed and the analogy between RMF current drive and the polyphase induction motor is explained. The general relationship between the energy and angular momentum transfer is utilized to calculate the efficiency of the RMF plasma current drive. It is found that relatively high efficiencies can be achieved in RMF current drive because of the low phase velocity and small slip between the rotating field and the electron fluid.

The orbits of electrons and ions in the fields of the rotamak

1987 ◽  
Vol 37 (1) ◽  
pp. 1-13 ◽  
Author(s):  
W. N. Hugrass ◽  
M. Turley
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Charged Particles ◽  
The Self ◽  
Rotating Magnetic Field ◽  
Plasma Equilibrium ◽  
Rotating Magnetic Fields ◽  
Cylindrical Plasma ◽  
Electrons And Ions ◽  
Self Consistent

The motion of electrons and ions in the self-consistent fields of a compact toroidal equilibrium maintained by means of a rotating magnetic field is studied. It is found that the particles are confined although the lines of the instantaneous magnetic field are open. The results are compared with those obtained in an earlier study of the motion of charged particles in the self-consistent fields appropriate to cylindrical plasma equilibrium maintained by means of rotating magnetic fields.

Behaviors of Bio-Functionalized Magnetic Nanoparticle Clusters in a Rotating Magnetic Field

2012 ◽  
Author(s):  
Chin-Yih Hong ◽  
Ji-Ching Lai ◽  
Chia-Chung Tang
Keyword(s):  
Magnetic Field ◽  
Aqueous Solution ◽  
Magnetic Nanoparticles ◽  
Magnetic Fields ◽  
Magnetic Nanoparticle ◽  
Critical Diameter ◽  
Rotating Magnetic Field ◽  
Magnetic Clusters ◽  
Rotating Magnetic Fields ◽  
Nanoparticle Clusters

Manipulation of magnetic nanoparticles has many applications in several fields and the behaviors of magnetic nanoparticles subjected to rotating or alternating magnetic fields attracted more attention from biomedical applications. In an aqueous solution containing bio-functionalized magnetic nanoparticles, due to the interaction between biomolecules, these nanoparticles agglomerate and form clusters with various sizes and shapes. In this study, the behaviors of magnetic nanoparticle clusters in an aqueous solution under rotating magnetic fields were investigated. Due to the interaction between the rotating magnetic field and the net magnetic dipole moment, the clusters were subjected to forced vibration. Two motion modes of clusters were observed as the magnetic field rotated. These two modes are rotation and oscillation. The diameters of the magnetic clusters with rotational or oscillational motions were measured. A critical diameter range of magnetic cluster was defined and the range is between 10.21 μm and 6.17 μm that could be used to distinguish rotation and oscillation of clusters.

scholarly journals Optical Imaging of Magnetic Particle Cluster Oscillation and Rotation in Glycerol

2021 ◽  
Vol 7 (5) ◽  
pp. 82
Author(s):  
River Gassen ◽  
Dennis Thompkins ◽  
Austin Routt ◽  
Philippe Jones ◽  
Meghan Smith ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Magnetic Particle ◽  
Barium Hexaferrite ◽  
Optical Microscope ◽  
Simplified Model ◽  
Particle Cluster ◽  
Average Deviation ◽  
Cross Sectional

Magnetic particles have been evaluated for their biomedical applications as a drug delivery system to treat asthma and other lung diseases. In this study, ferromagnetic barium hexaferrite (BaFe12O19) and iron oxide (Fe3O4) particles were suspended in water or glycerol, as glycerol can be 1000 times more viscous than water. The particle concentration was 2.50 mg/mL for BaFe12O19 particle clusters and 1.00 mg/mL for Fe3O4 particle clusters. The magnetic particle cluster cross-sectional area ranged from 15 to 1000 μμm2, and the particle cluster diameter ranged from 5 to 45 μμm. The magnetic particle clusters were exposed to oscillating or rotating magnetic fields and imaged with an optical microscope. The oscillation frequency of the applied magnetic fields, which was created by homemade wire spools inserted into an optical microscope, ranged from 10 to 180 Hz. The magnetic field magnitudes varied from 0.25 to 9 mT. The minimum magnetic field required for particle cluster rotation or oscillation in glycerol was experimentally measured at different frequencies. The results are in qualitative agreement with a simplified model for single-domain magnetic particles, with an average deviation from the model of 1.7 ± 1.3. The observed difference may be accounted for by the fact that our simplified model does not include effects on particle cluster motion caused by randomly oriented domains in multi-domain magnetic particle clusters, irregular particle cluster size, or magnetic anisotropy, among other effects.

Numerical Study of the Effect of Magnetic Fields on Melt-Crystal Interface-Deflection in Czochralski Crystal Growth

2003 ◽  
Author(s):  
Lijun Liu ◽  
Koichi Kakimoto
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Numerical Study ◽  
Silicon Crystal ◽  
Czochralski Growth ◽  
Thermal Flow ◽  
Interface Shape ◽  
Convective Thermal ◽  
And Control ◽  
Crystal Interface

In order to control the impurity distribution and remove defects in a crystal grown in Czochralski growth for high quality crystals of silicon, it is necessary to study and control the melt-crystal interface shape, which plays an important role in control of the crystal quality. The melt-crystal interface interacts with and is determined by the convective thermal flow of the melt in the crucible. Application of magnetic field in the Czochralski system is an effective tool to control the convective thermal flow in the crucible. Therefore, the shape of the melt-crystal interface can be modified accordingly. Numerical study is performed in this paper to understand the effect of magnetic field on the interface deflection in Czochralski system. Comparisons have been carried out by computations for four arrangements of the magnetic field: without magnetic field, a vertical magnetic field and two types of cusp-shaped magnetic field. The velocity, pressure, thermal and electromagnetic fields are solved with adaptation of the mesh to the iteratively modified interface shape. The multi-block technique is applied to discretize the melt field in the crucible and the solid field of silicon crystal. The unknown shape of the melt-crystal interface is achieved by an iterative procedure. The computation results show that the magnetic fields have obvious effects on both the pattern and strength of the convective flow and the interface shape. Applying magnetic field in the Czochralski system, therefore, is an effective tool to control the quality of bulk crystal in Czochralski growth process.

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