scholarly journals On-demand Ferrofluid Droplet Formation With Non-linear Magnetic Permeability in the Presence of a Non-uniform Magnetic Field

2021 ◽  
Author(s):  
Mohamad Ali Bijarchi ◽  
Mohammad Yaghoobi ◽  
Amirhossein Favakeh ◽  
Mohammad Behshad Shafii
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Uniform Magnetic Field ◽  
Maxwell Equations ◽  
Droplet Diameter ◽  
Droplet Formation ◽  
Bond Number ◽  
On Demand ◽  
Drop On Demand ◽  
The Magnetic Field

Abstract The magnetic actuation of ferrofluid droplets offers an inspiring tool in widespread engineering and biological applications. In this study, the dynamics of ferrofluid droplet generation with a Drop-on-Demand feature under a non-uniform magnetic field is investigated by multiscale numerical modeling. Langevin equation is assumed for ferrofluid magnetic susceptibility due to the strong applied magnetic field. Large and small computational domains are considered. In the larger domain, the magnetic field is obtained by solving Maxwell equations. In the smaller domain, a coupling of continuity, Navier Stokes, two-phase flow, and Maxwell equations are solved by utilizing the magnetic field achieved by the larger domain for the boundary condition. The Finite volume method and coupling of level-set and Volume of Fluid methods are used for solving equations. The droplet formation is simulated in a two-dimensional axisymmetric domain. The method of solving fluid and magnetic equations is validated using a benchmark. Then, ferrofluid droplet formation is investigated experimentally and the numerical results are in good agreement with the experimental data. The effect of 12 dimensionless parameters including the ratio of magnetic, gravitational, and surface tension forces, the ratio of the nozzle and magnetic coil dimensions, and ferrofluid to continuous-phase properties ratios are studied. The results showed that by increasing the magnetic Bond number, gravitational Bond number, Ohnesorge number, dimensionless saturation magnetization, initial magnetic susceptibility of ferrofluid, the generated droplet diameter reduces, whereas the formation frequency increases. The same results were observed when decreasing the ferrite core diameter to outer nozzle diameter, density, and viscosity ratios.

scholarly journals A Rapid Magnetofluidic Micromixer Using Diluted Ferrofluid

2016 ◽  
Author(s):  
Majid Hejazian ◽  
Nam-Trung Nguyen
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
External Magnetic Field ◽  
Uniform Magnetic Field ◽  
Body Force ◽  
Low Cost ◽  
Magnetic Field Gradient ◽  
Mixing Efficiency ◽  
Biological Assays ◽  
The Magnetic Field

Effective and rapid mixing is essential for various chemical and biological assays. The present work reports a simple and low-cost micromixer based on magnetofluidic actuation. The device takes advantage of magnetoconvective secondary flow, a bulk flow induced by an external magnetic field, for mixing. A paramagnetic stream of diluted ferrofluid and a non-magnetic stream are introduced to a straight microchannel. A permanent magnet placed next to the microchannel induced a non-uniform magnetic field. The magnetic field gradient and the mismatch in magnetic susceptibility between the two streams create a body force, which leads to rapid and efficient mixing. The micromixer reported here could achieve a high throughput and a high mixing efficiency of 90 % in a relatively short microchannel.

Alternating Force Based Drop-on-Demand Microdroplet Formation and Three-Dimensional Deposition

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Long Zhao ◽  
Karen Chang Yan ◽  
Rui Yao ◽  
Feng Lin ◽  
Wei Sun
Keyword(s):  
Process Parameters ◽  
Droplet Diameter ◽  
Three Dimensional ◽  
Inertial Force ◽  
Deposition Process ◽  
Droplet Formation ◽  
Solution Viscosity ◽  
Cell Printing ◽  
On Demand ◽  
Drop On Demand

Drop-on-demand (DOD) microdroplet formation and deposition play an important role in additive manufacturing, particularly in printing of three-dimensional (3D) in vitro biological models for pharmacological and pathological studies, for tissue engineering and regenerative medicine applications, and for building of cell-integrated microfluidic devices. In development of a DOD based microdroplet deposition process for 3D cell printing, the droplet formation, controlled on-demand deposition and at the single-cell level, and most importantly, maintaining the viability and functionality of the cells during and after the printing are all remaining to be challenged. This report presents our recent study on developing a novel DOD based microdroplet deposition process for 3D printing by utilization of an alternating viscous and inertial force jetting (AVIFJ) mechanism. The results include an analysis of droplet formation mechanism, the system configuration, and experimental study of the effects of process parameters on microdroplet formation. Sodium alginate solutions are used for microdroplet formation and deposition. Key process parameters include actuation signal waveforms, nozzle dimensional features, and solution viscosity. Sizes of formed microdroplets are examined by measuring the droplet diameter and velocity. Results show that by utilizing a nozzle at a 45 μm diameter, the size of the formed microdroplets is in the range of 52–72 μm in diameter and 0.4–2.0 m/s in jetting speed, respectively. Reproducibility of the system is also examined and the results show that the deviation of the formed microdroplet diameter and the droplet deposition accuracy is within 6% and 6.2 μm range, respectively. Experimental results demonstrate a high controllability and precision for the developed DOD microdroplet deposition system with a potential for precise cell printing.

Pressure and Temperature Effects on the Magnetic Properties of Donor Impurities in a GaAs/AlGaAs Quantum Heterostructure Subjected to a Magnetic Field

2021 ◽  
Vol 14 (3) ◽  
pp. 231-238
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Uniform Magnetic Field ◽  
Growth Direction ◽  
Exact Diagonalization ◽  
Donor Impurity ◽  
Diagonalization Method ◽  
Exact Diagonalization Method ◽  
Pressure And Temperature Effects ◽  
The Magnetic Field

Abstract: The exact diagonalization method has been used to solve the effective-mass Hamiltonian of a single electron confined parabolically in the GaAs/AlGaAs quantum heterostructure, in the presence of a donor impurity and under the effect of an applied uniform magnetic field. The donor impurity is located at distance (d) along the growth direction which is perpendicular to the motion of the electron in a two-dimensional heterostructure layer. We have investigated the dependence of the magnetization (M) and magnetic susceptibility (χ) of a GaAs/AlGaAs quantum heterostructure nanomaterial on the magnetic field strength (ω_c), confining frequency (ω_o), donor impurity position (d), pressure (P) and temperature (T). Keywords: Exact diagonalization, Donor impurity, Magnetic field, Magnetization, Magnetic susceptibility, Pressure and temperature.

The stability of viscous flow in a curved channel in the presence of a magnetic field

1961 ◽  
Vol 264 (1317) ◽  
pp. 155-164 ◽  
Keyword(s):  
Magnetic Field ◽  
Viscous Flow ◽  
Uniform Magnetic Field ◽  
Axial Direction ◽  
Electrical Conductor ◽  
Curved Channel ◽  
Coaxial Cylinders ◽  
Transverse Pressure ◽  
The Stability ◽  
The Magnetic Field

The stability of viscous flow between two coaxial cylinders maintained by a constant transverse pressure gradient is considered when the fluid is an electrical conductor and a uniform magnetic field is impressed in the axial direction. The problem is solved and the dependence of the critical number for the onset of instability on the strength of the magnetic field and the coefficient of electrical conductivity of the fluid is determined.

scholarly journals Spin-1/2 Particles under the Influence of a Uniform Magnetic Field in the Interior Schwarzschild Solution

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 467
Author(s):  
Fayçal Hammad ◽  
Alexandre Landry ◽  
Parvaneh Sadeghi
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Total Mass ◽  
Uniform Magnetic Field ◽  
Energy Levels ◽  
Relativistic Wave Equation ◽  
Relativistic Wave ◽  
Schwarzschild Solution ◽  
Relativistic Regime ◽  
The Magnetic Field

The relativistic wave equation for spin-1/2 particles in the interior Schwarzschild solution in the presence of a uniform magnetic field is obtained. The fully relativistic regime is considered, and the energy levels occupied by the particles are derived as functions of the magnetic field, the radius of the massive sphere and the total mass of the latter. As no assumption is made on the relative strengths of the particles’ interaction with the gravitational and magnetic fields, the relevance of our results to the physics of the interior of neutron stars, where both the gravitational and the magnetic fields are very intense, is discussed.

Numerical analysis of the magnetic field for arbitrary magnetic susceptibility distributions in 3D

1994 ◽  
Vol 12 (1) ◽  
pp. 101-107 ◽  
Author(s):  
R. Bhagwandien ◽  
M.A. Moerland ◽  
C.J.G. Bakker ◽  
R. Beersma ◽  
J.J.W. Lagendijk
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Numerical Analysis ◽  
The Magnetic Field

scholarly journals Magnetic micropump embedded in contact lens for on-demand drug delivery

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Cong Wang ◽  
Jungyul Park
Keyword(s):  
Magnetic Field ◽  
Drug Delivery ◽  
External Magnetic Field ◽  
Drug Release ◽  
Contact Lens ◽  
Tear Film ◽  
Check Valve ◽  
Drug Diffusion ◽  
On Demand ◽  
The Magnetic Field

AbstractIn this paper, we report a thin magnetic micropump embedded in contact lens, which is capable of on-demand one-directional drug delivery. The proposed micropump can be actuated by the external magnetic field whenever needed without the need of battery. A micro check valve was integrated with the micropump for one-directional drug delivery from the micropump to the post-lens tear film. With actuation of the external magnetic field, the micro check valve is opened, and on-demand drug release can be realized. On the contrary, without an external magnetic field, the micro check valve is closed, and the undesired drug diffusion can be prevented. Through the control of the strength and the frequency of the magnetic field pulse, on-demand drug release and controlled dose can be realized.

scholarly journals Deformation of a magnetic liquid drop in an applied non-stationary uniform magnetic field

2018 ◽  
Vol 185 ◽  
pp. 09006
Author(s):  
Alexander Tyatyushkin
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Steady State ◽  
Uniform Magnetic Field ◽  
Liquid Drop ◽  
Magnetic Liquid ◽  
Stationary Approximation ◽  
The Magnetic Field

Small steady-state deformational oscillations of a drop of magnetic liquid in a nonstationary uniform magnetic field are theoretically investigated. The drop is suspended in another magnetic liquid immiscible with the former. The Reynolds number is so small that the inertia can be neglected. The variation of the magnetic field is so slow that the quasi-stationary approximation for the magnetic field and the quasi-steady approximation for the flow may be used.

Textured Beta-Sialon:Eu2+ Phosphor Deposits Fabricated by Electrophoretic Deposition (EPD) Process within a Strong Magnetic Field: Preparation Process and Photoluminescence (PL) Properties Depending on Orientation

2015 ◽  
Vol 654 ◽  
pp. 268-273
Author(s):  
Chen Ning Zhang ◽  
Tetsuo Uchikoshi ◽  
Li Hong Liu ◽  
Benjamin Dierre ◽  
Yu Jin Cho ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Electric Field ◽  
Strong Magnetic Field ◽  
Electrophoretic Deposition ◽  
Intensity Ratio ◽  
Preparation Process ◽  
Crystal Axis ◽  
Chromaticity Coordinates ◽  
The Magnetic Field

Beta-sialon:Eu2+ phosphor deposits were fabricated by electrophoretic deposition (EPD) process within a strong magnetic field (12 T). The direction of the magnetic field was adjusted to be parallel or perpendicular to that of the electric field, that is, vertical-or horizontal setup. The oriented deposits were fabricated by aligning the β-sialon:Eu2+ particles along the higher magnetic-susceptibility c-crystal axis (a, b-crystal plane). For the case of vertically-setup magnetic field, the oriented deposit aligned along the c-axis possessed higher relative deposit density than the randomly fabricated deposit, as a result, varying the intensity ratio of emission and transmitted excitation, and therefore, presenting different chromaticity coordinates; for the case of horizontally-setup magnetic field, photoluminescence (PL) intensities of the deposits oriented along c-axis were significantly improved by comparing with those of the randomly-oriented ones.

Effect of Magnetic Field on the Laminar Heat Transfer Performance of Hybrid Nanofluid in a Lid Driven Cavity Over Solid Block

2020 ◽  
Author(s):  
Rajesh Nimmagadda ◽  
Durga Prakash Matta ◽  
Rony Reuven ◽  
Lazarus Godson Asirvatham ◽  
Somchai Wongwises ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Uniform Magnetic Field ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Performance ◽  
Hybrid Nanofluid ◽  
Transfer Performance ◽  
Driven Cavity ◽  
The Magnetic Field ◽  
Solid Block

Abstract A 2D numerical investigation has been carried out to obtain the heat transfer performance of hybrid (Al2O3 + Ag) nanofluid in a lid driven cavity over solid block under the influence of uniform as well as non-uniform magnetic field. The geometrical domain consists of a cavity containing nanofluid that is driven by means of lid moving in one direction. This circulating nanofluid will extract enormous amount of heat from the solid block underneath the cavity resulting in conjugate heat transfer. A homogenous solver based on the finite volume method with conjugate heat transfer was developed and adopted in the existing study. The heat efficient hybrid nanofluid (HyNF) pair (2.4 vol.% Ag + 0.6 vol.% Al2O3) obtained by Nimmagadda and Venkatasubbaiah [1] is used in the present investigation. Moreover, efficient non-uniform sinusoidal magnetic field identified by Nimmagadda et al. [2] is also implemented and compared with uniform magnetic field. Furthermore, the magnetic field is applied over the geometrical domain along the two axial directions separately and the effective heat transfer performance is obtained. The significant impact of extensive parameters like Reynolds number, nanoparticle type, nanoparticle concentration, magnetic field type, magnetic field location and the strength of the magnetic field on heat transfer performance are systematically analyzed and presented.

Sign in / Sign up

Export Citation Format

Share Document