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.

On Electrical Conductivity Measurements of Molten Metals by Inductive Technique

2004 ◽  
Vol 126 (3) ◽  
pp. 468-470 ◽  
Author(s):  
Sayavur I. Bakhtiyarov ◽  
Mihai Dupac ◽  
Ruel A. Overfelt ◽  
Sorin G. Teodorescu
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Electrical Conductivity ◽  
Fluid Flow ◽  
External Magnetic Field ◽  
Electric Conductivity ◽  
Molten Metals ◽  
Conductivity Measurements ◽  
Permanent Magnetic Field ◽  
Rotating Liquid

In this paper, we propose a new relationship between the opposing mechanical torque and the electric conductivity of a rotating liquid specimen in a permanent external magnetic field of constant induction, which includes the effect of fluid flow. The proposed relationship was applied to describe the experimental data for a conductive specimens rotating in a permanent magnetic field.

Fluid Flow Effect in Electrical Conductivity Measurements of Molten Metals by Inductive Technique

2002 ◽  
Author(s):  
Sayavur I. Bakhtiyarov ◽  
Mihai Dupac ◽  
Ruel A. Overfelt ◽  
Sorin G. Teodorescu
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Electrical Conductivity ◽  
Fluid Flow ◽  
External Magnetic Field ◽  
Electric Conductivity ◽  
Molten Metals ◽  
Conductivity Measurements ◽  
Permanent Magnetic Field ◽  
Rotating Liquid

In this paper we propose a new relationship between the opposing mechanical torque and the electric conductivity of a rotating liquid specimen in a permanent external magnetic field of constant induction, which includes the effect of fluid flow. The proposed relationship was applied to describe the experimental data for a conductive specimen rotating in a permanent magnetic field.

scholarly journals Imbalance Detection of Rotor Rotational Speed Using Doppler Radar

2021 ◽  
Vol 21 (2) ◽  
pp. 111-118
Author(s):  
Young-Jae Choi ◽  
In-Sik Choi
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Wind Turbine ◽  
Rotational Speed ◽  
Doppler Radar ◽  
Numerical Data ◽  
Accumulated Damage ◽  
The Difference

In operating a wind turbine, both predictive and condition-based maintenances are required to minimize the downtime caused by maintenance. The imbalance of rotor rotational speed is an important factor for diagnosing wind turbine failures. The rotational speed imbalance can be caused by accumulated damage or the accumulation of ice, dust, and moisture. In this paper, we proposed a method for detecting the rotational speed imbalance of a wind turbine using a Doppler radar. We calculated the difference in the rotational speed for different times using spectrograms obtained by observing the wind turbine with a Doppler radar and determined the rotational speed imbalance using the fast Fourier transform. The performance of the proposed algorithm was verified using both synthetic and numerical data.

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.

Three-dimensional magnetic field analysis of micromotor by fast Fourier transform

1999 ◽  
Vol 35 (5) ◽  
pp. 3685-3687 ◽  
Author(s):  
Mingsheng Zhang ◽  
Bingcu Cai ◽  
Xiaolin Zhao ◽  
Zongguang Wang
Keyword(s):  
Magnetic Field ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Three Dimensional ◽  
Field Analysis ◽  
Magnetic Field Analysis

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.

scholarly journals Исследование связанной динамики магнитных вихрей в трехслойном проводящем наноцилиндре

2018 ◽  
Vol 60 (6) ◽  
pp. 1045
Author(s):  
С.В. Степанов ◽  
А.Е. Екомасов ◽  
К.А. Звездин ◽  
Е.Г. Екомасов
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Vortex Motion ◽  
Numerical Data ◽  
Sample Plane ◽  
Current Dependence ◽  
Magnetic Vortices ◽  
Lifshitz Equation ◽  
Spin Polarized ◽  
Stationary Vortex

AbstractSolving numerically the generalized Landau–Lifshitz equation, we have carried out the micromagnetic investigation of the dynamics of two dipole-coupled magnetic vortices in a trilayer nanocolumn under the action of the external magnetic field directed perpendicular to the sample plane and spin-polarized electric field. The possible existence of different regimes of vortex motion, depending on the polarized current, is demonstrated. The current dependence of the oscillation frequency for the case of stationary dynamics of coupled vortices with the same frequency has been established. The possibility of controlling the frequency of the stationary vortex motion and tuning the control current amplitude by the external magnetic field is shown. Using the analytical method for simplified description of the dynamics of coupled vortices, the current and magnetic-field dependences of the frequency have been obtained, which are qualitatively consistent with the numerical data.

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