Dipole-Dipole Interaction Between Particle Complexes in a Magnetophoretic Bioseparation Chip

2016 ◽  
Author(s):  
Manjurul Alam ◽  
Jeff Darabi
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Microfluidic Device ◽  
Applied Magnetic Field ◽  
Particle Motion ◽  
Computational Study ◽  
Particle Interaction ◽  
Dipole Interaction ◽  
Interaction Force ◽  
Particle Trajectories

Particle-particle interaction is an important phenomenon in the analysis of particle transport in a microfluidic device. This paper presents a computational study to predict the interaction force between particle complexes in a magnetophoretic bio-separation chip. Magnetic flux gradients are simulated in OpenFOAM CFD software and imported to Matlab to obtain the particle trajectories. The interaction force is approximated using a dipole based model and implemented to track the particle motion in a microfluidic device in the presence of an applied magnetic field. The analysis of particle trajectories is performed for cases where the applied magnetic field is parallel or perpendicular to the inter-particle distance of the particle complexes by solving a system of coupled ordinary differential equations.

QUANTUM EFFECTS DUE TO A MAGNETIC FLUX ASSOCIATED TO A TOPOLOGICAL DEFECT

2005 ◽  
Vol 20 (26) ◽  
pp. 6051-6064 ◽  
Author(s):  
GEUSA DE A. MARQUES ◽  
V. B. BEZERRA ◽  
C. FURTADO ◽  
F. MORAES
Keyword(s):  
Magnetic Field ◽  
Wave Function ◽  
Magnetic Flux ◽  
Applied Magnetic Field ◽  
Bound States ◽  
Topological Defect ◽  
Energy Spectra ◽  
Quantum Scattering ◽  
Bohm Effect ◽  
Aharonov Bohm

We investigate the quantum scattering of an electron by a topological defect called dispiration, with an externally applied magnetic field along its axis. The Aharonov–Bohm effect for bound states is analyzed and it is demonstrated that the wave function and the energy spectra associated with the particle depend on the features of the dispiration as well as on the magnetic flux. We also calculate Berry's phase associated to the dynamics of electrons in this background.

scholarly journals Waves Generated by Electron Beam in a Crater-Shaped Flux Rope

2021 ◽  
Vol 9 ◽  
Author(s):  
Kyunghwan Dokgo ◽  
Kyoung-Joo Hwang ◽  
James L. Burch ◽  
Peter H. Yoon
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Power Spectrum ◽  
Magnetic Flux ◽  
Particle Interaction ◽  
Outer Region ◽  
Flux Rope ◽  
Electrostatic Wave ◽  
Magnetic Flux Rope ◽  
Parallel Mode

Understanding the nature and characteristics of high-frequency waves inside a flux rope may be important as the wave-particle interaction is important for charged-particle energization and the ensuing dissipation process. We analyze waves generated by an electron beam in a crater-shaped magnetic flux rope observed by MMS spacecraft on the dawnside tailward magnetopause. In this MMS observation, a depression of magnetic field, or a crater, of ∼100 km is located at the center of the magnetic flux rope of ∼650 km. There exist parallel and perpendicular electrostatic wave modes inside the depression of the magnetic field at the center of the flux rope, and they are distinguished by their locations and frequencies. The parallel mode exists at the center of the magnetic depression and its power spectrum peaks below Fce (electron cyclotron frequency). In contrast, the perpendicular mode exists in the outer region associated with the magnetic depression, and its power spectrum peaks near Fce. The linear analysis of kinetic instability using a generalized dispersion solver shows that the parallel mode can be generated by the electron beam of 5,000 km/s. They can thermalize electrons ≲100 eV effectively. However, the generation mechanism of the perpendicular mode is not clear yet, which requires further study.

Anti-function solution of uniaxial anisotropic Stoner-Wohlfarth model

2021 ◽  
Author(s):  
Kun Zheng ◽  
Yu Miao ◽  
Tong Li ◽  
Shuang-Long Yang ◽  
Li Xi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Magnetization Reversal ◽  
Analytic Solution ◽  
Hysteresis Loops ◽  
Anisotropy Field ◽  
Dipole Interaction ◽  
Trigonometric Function ◽  
Switching Field ◽  
Function Solution

Abstract The anti-trigonometric function is used to strictly solve the uniaxial anisotropic Stoner-Wohlfarth (SW) model, which can obtain the relation of the angle α (θ) between the magnetization (the anisotropy field) and the applied magnetic field. Using this analytic solution, the hysteresis loops of uniaxial anisotropic SW particles magnetized in typical directions could be numerically calculated. Then, the hysteresis loops are obtained in randomly distributed SW particle ensembles while ignoring the dipole interaction among them with the analytic solution. Finally, the correctness of the analytic solution is verified by the exact solutions of remanence, switching field, and coercivity from SW model. The analytic solution provides an important reference for understanding the magnetizing and magnetization reversal processes of magnetic materials.

scholarly journals Influence of the Drop Volume and Applied Magnetic Field on the Wetting Features of Water-based Ferrofluids

2020 ◽  
Vol 5 (9) ◽  
pp. 1110-1116
Author(s):  
Barenten Suciu
Keyword(s):  
Magnetic Field ◽  
Contact Angle ◽  
Magnetic Flux ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Permanent Magnets ◽  
Field Energy ◽  
Drop Volume ◽  
Magnetic Field Energy ◽  
Water Based

In this work, the influence of the drop volume and applied magnetic field on the wetting features of water-based ferrofluids, is experimentally investigated. Firstly, water drops with volume in the range of 0.1–100 micro-liters are placed, by using micro-pipettes, on bare and coated acrylic plates, to gain reference data concerning the contact angle. Then, drops of water-based ferrofluid, with the volume ranging from 1 to 10 micro-liters, are set on bare acrylic plates, which are placed into the uniform magnetic field created, in normal direction to the plate, by using permanent magnets. Since the ferrofluid drops are elongated along the magnetic field, the contact angle increases at augmentation of the magnetic flux. Besides, when a critical magnetic flux is exceeded, ferrofluid drop loose contact with the plate and jumps towards the magnet. A heuristic equation to predict the fluctuation of the liquid surface tension versus the drop volume, and also versus the ratio of the applied magnetic field energy to the kinetic energy of the magnetic particles dispersed into the water-based ferrofluid, is suggested.

Magnetic States of Nanodot Arrays. Physical and Numerical Experiments

2010 ◽  
Vol 168-169 ◽  
pp. 325-328 ◽  
Author(s):  
K. Nefedev ◽  
Y. Ivanov ◽  
A. Peretyatko ◽  
V. Belokon
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Numerical Experiments ◽  
Research Method ◽  
Dipole Interaction ◽  
Interaction Force ◽  
Space Distribution ◽  
Nanodot Arrays ◽  
2D Arrays ◽  
Magnetic States

The research method for the investigation of magnetic states of single nanoparticles, 1D arrays, 2D, and quasi-2D arrays is used. The possibility of the nanodots magnetic states reconstruction by the space distribution of gradient dipole-dipole interaction force is theoretically justified. The comparison is made between the results of nanoarchitecture numerical simulation in an external magnetic field and experimental data.

Magnetic dipole interaction with multipole magnetic field lines of neutron stars

2021 ◽  
Author(s):  
Habtamu Menberu Tedila
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Neutron Stars ◽  
Field Line ◽  
Dipole Interaction ◽  
Line Geometry ◽  
Magnetic Dipole Interaction ◽  
Field Lines ◽  
The Magnetic Field

AbstractConservation of magnetic flux is associated with regions of the powerful magnetic fields (B ∽ 1013 G) near neutron stars' surface. The vector potential generated by moving electric charge Q is uniformly distributed within a Neutron star's surface (radius R). The evolution of the magnetic field of isolated neutron stars is studied and based on magnetic flux conservation; the multipolar magnetic fields for (l = 1; l = 2; l  = 3; l  = 4) have calculated. We developed the field line equations and simulated the magnetic field line geometry for the interaction between neutron stars’ dipole–multipolar magnetic fields using the MATLAB software program.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

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