Numerical Simulation of Magnetic Fluid Used in Sintering and Cooling Equipments Seals as a Functional Material

2011 ◽  
Vol 239-242 ◽  
pp. 3096-3099
Author(s):  
Ming Hua Bai ◽  
Hong Liang Zhou
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
External Magnetic Field ◽  
Magnetic Fluid ◽  
Permanent Magnets ◽  
Quiescent State ◽  
Flow State ◽  
Functional Material ◽  
Volume Force

Magnetic fluid as a functional material can produce volume force under external magnetic field, for the purpose of controlling the magnetic fluid flow state in the non-magnetic sealing groove with external magnetic field, the volume force is written as a function form of AZ to do with the numerical simulation of magnetic fluid flow in the sealing groove. The result shows that the magnetic fluid which distributes at the right-angle edges of the two permanent magnets nearby the separator presents unsteady swirl flow due to the volume force, while the rest magnetic fluid is in the quiescent state. It means that the magnetic fluid seal method can effectively solve the air leakage of band sintering machine and circular cooling machine.

scholarly journals Self-assembled artificial cilia

2009 ◽  
Vol 107 (5) ◽  
pp. 1844-1847 ◽  
Author(s):  
Mojca Vilfan ◽  
Anton Potočnik ◽  
Blaž Kavčič ◽  
Natan Osterman ◽  
Igor Poberaj ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Fluid Flow ◽  
External Magnetic Field ◽  
Low Reynolds Number ◽  
Microfluidic Devices ◽  
Superparamagnetic Particles ◽  
Artificial Cilia ◽  
Biomimetic Cilia

Due to their small dimensions, microfluidic devices operate in the low Reynolds number regime. In this case, the hydrodynamics is governed by the viscosity rather than inertia and special elements have to be introduced into the system for mixing and pumping of fluids. Here we report on the realization of an effective pumping device that mimics a ciliated surface and imitates its motion to generate fluid flow. The artificial biomimetic cilia are constructed as long chains of spherical superparamagnetic particles, which self-assemble in an external magnetic field. Magnetic field is also used to actuate the cilia in a simple nonreciprocal manner, resulting in a fluid flow. We prove the concept by measuring the velocity of a cilia-pumped fluid as a function of height above the ciliated surface and investigate the influence of the beating asymmetry on the pumping performance. A numerical simulation was carried out that successfully reproduced the experimentally obtained data.

Simulation of Flow Control in Microchannels Using Ferrofluid Plugs

2009 ◽  
Author(s):  
Akshay C. Gunde ◽  
Sushanta K. Mitra
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
External Magnetic Field ◽  
Flow Control ◽  
Microfluidic Devices ◽  
Alternative Methods ◽  
Mechanical Components ◽  
Important Position ◽  
The Relationship

Microfluidic devices have acquired an important position in the field of MEMS. While the usage of mechanical components for achieving electroosmosis and electrophoresis effects can prove to be impractical and costly, alternative methods for flow control have to be explored. This paper extends the concept of obtaining a superior flow control in microchannels by using ferrofluid plugs as barriers. These plugs occlude and discharge fluid flow, thereby functioning as valves and rendering the usage of mechanical components unnecessary. A numerical simulation of a ferrofluid plug blocking fluid flow in a microchannel due to the action of a magnetic field is carried out. The relationship between ferrofluid property and the capacity to block fluid flow is studied and analyzed. Thus a new concept of flow control in a microfluidic device by the proper variation of the external magnetic field and positioning of the ferrofluid plugs has been introduced.

scholarly journals Magnetoviscosity of a Magnetic Fluid Based on Barium Hexaferrite Nanoplates

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1870
Author(s):  
Dmitry Borin ◽  
Robert Müller ◽  
Stefan Odenbach
Keyword(s):  
Magnetic Field ◽  
Experimental Study ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
Shear Flow ◽  
Magnetic Fluid ◽  
Barium Hexaferrite ◽  
Dipole Interaction ◽  
Field Dependent ◽  
Fluid Behaviour

This paper presents the results of an experimental study of the influence of an external magnetic field on the shear flow behaviour of a magnetic fluid based on barium hexaferrite nanoplates. With the use of rheometry, the magnetoviscosity and field-dependent yield-stress in the fluid are evaluated. The observed fluid behaviour is compared to that of ferrofluids with magnetic nanoparticles having high dipole interaction. The results obtained supplement the so-far poorly studied topic of the influence of magnetic nanoparticles’ shape on magnetoviscous effects. It is concluded that the parameter determining the observed magnetoviscous effects in the fluid under study is the ratio V2/l3, where V is the volume of the nanoparticle and l is the size of the nanoparticle in the direction corresponding to its orientation in the externally applied magnetic field.

Numerical Simulation of High-Aspect-Ratio Micro-Hole Electroforming with External Magnetic Field

2010 ◽  
Vol 42 ◽  
pp. 13-16
Author(s):  
Wei Li ◽  
Ping Mei Ming ◽  
Wu Ji Jiang ◽  
Yin Ding Lv
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Flow State ◽  
Cathode Electrode ◽  
Micro Hole ◽  
Fluent Software ◽  
The Magnetic Field ◽  
Enhance Mass

In this paper, the influences of applied magnetic field on flow state during electroforming of the high-aspect-ratio (HAR) blind micro-hole were numerically analyzed using the Fluent software. The results showed that, when microelectroforming of nickel without external agitation, three vortexes could form due to the magnetohydrodynamic (MHD) effect within the HAR micro-hole with magnetic field in parallel to cathode-electrode surface, and the flow rate in the micro-hole increased with the increase of the magnetic field and current density. The MHD effect helped to enhance mass transfer during the microelectroforming of HAR microstructures.

scholarly journals An Analysis of a Laminar-Turbulent Transition and Thermal Plumes Behavior in a Paramagnetic Fluid Subjected to an External Magnetic Field

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7972
Author(s):  
Anna Kraszewska ◽  
Janusz Donizak
Keyword(s):  
Magnetic Field ◽  
Fourier Transform ◽  
Fluid Flow ◽  
External Magnetic Field ◽  
Fast Fourier Transform ◽  
Numerical Data ◽  
Superconducting Magnet ◽  
Transition To Turbulence ◽  
Thermal Plume ◽  
Numerical Research

Transition to turbulence and changes in the fluid flow structure are subjects of continuous analysis and research, especially for unique fields of research such as the thermo-magnetic convection of weakly magnetic fluids. Therefore, an experimental and numerical research of the influence of an external magnetic field on a natural convection’s fluid flow was conducted in the presented research. The experimental part was performed for an enclosure with a 0.5 aspect ratio, which was filled with a paramagnetic fluid and placed in a superconducting magnet in a position granting the enhancement of the flow. The process was recorded as temperature signals from the thermocouples placed in the analyzed fluid. The numerical research enabled an investigation based not only on temperature, but velocities as well. Experimental and numerical data were analyzed with the application of extended fast Fourier transform and wavelet analysis. The obtained results allowed the determination of changes in the nature of the flow and visualization of the influence of an imposed strong magnetic field on a magnetic fluid. It is proved that an applied magnetic field actuates the flow in Rayleigh-Benard convection and causes the change from laminar to turbulent flow for fairly low magnetic field inductions (2T and 3T for ΔT = 5 and 11 °C respectively). Fast Fourier transform allowed the definition of characteristic frequencies for oscillatory states in the flow, as well as an observation that the high values of magnetic field elongate the inertial range of the flow on the power spectrum density. Temperature maps obtained during numerical simulations granted visualizations of thermal plume formation and behavior with increasing magnetic field.

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