scholarly journals Numerical study of magnetic particles mixing in waste water under an external magnetic field

2020 ◽  
Vol 69 (3) ◽  
pp. 266-275 ◽  
Author(s):  
Christos Liosis ◽  
Evangelos G. Karvelas ◽  
Theodoros Karakasidis ◽  
Ioannis E. Sarris
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Numerical Study ◽  
Low Frequency ◽  
Water And Wastewater Treatment ◽  
Novel Approach ◽  
Optimal Value ◽  
Frequency Optimum ◽  
Combined Action ◽  
Aligned Magnetic Field

Abstract The combination of nanotechnology and microfluidics may offer an effective water and wastewater treatment. A novel approach combines the use of magnetic particles which can capture heavy metal impurities in microfluidic ducts. The purpose of this study is to investigate the mixing mechanism of two water streams, one with magnetic particles and the other with wastewater. The optimum mixing is obtained when particles are uniformly distributed along the volume of water in the duct for the combined action of a permanent, spatially and temporally aligned magnetic field. Results showed that mixing is enhanced as the frequency of the magnetic field decreases or its amplitude increases, while magnetic gradient is found to play an insignificant role in the present configuration. Moreover, for simulations with low frequency, the mean concentration of particles is found to be twice as high as compared to the cases with higher frequency. Optimum distribution of particles inside the micromixer is observed for the combination of 0.6 T, 8 T/m and 5 Hz for the magnetic magnitude, gradient and frequency, respectively, where concentration reaches the optimal value of 0.77 mg/mL along the volume of the duct.

scholarly journals Magnetic field frequency optimisation for MFL imaging using QWHE sensors

2020 ◽  
Vol 62 (7) ◽  
pp. 396-401
Author(s):  
J M Watson ◽  
C W Liang ◽  
J Sexton ◽  
M Missous
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Power Consumption ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Permanent Magnets ◽  
Low Frequency ◽  
Step Size ◽  
Lift Off

Magnetic particle and other magnetic flux leakage (MFL)-based methods for the detection and evaluation of surfacebreaking flaws in ferromagnetic materials typically use high-strength (∼0.5 T RMS) low-frequency (≤50 Hz) magnetic fields. The rationale behind this is the ready availability of strong permanent magnets and mains power for highstrength electromagnets. This high field strength is needed to saturate the sample and compensate for the insensitivity of magnetic particles, silicon Hall sensors, coils and other magnetic transducers. Consequently, the frequency of the applied magnetic field is typically limited to ≤50 Hz and does not consider the frequency response of the material under test (some MFL applications use this low frequency to detect subsurface or flaws on the backwall). In this study, a probe consisting of a quantum well Hall-effect (QWHE) sensor, an illuminating electromagnet and sensor circuitry was controlled using an automated XYZ scanner with an x-y measurement step size (ie magnetic image pixel size) of 100 microns. This probe was used to apply magnetic fields of various frequencies (DC to 1 kHz) and field strengths (5 mT to 100 mT) to ascertain a frequency and field range best suited to detecting 10 mm- and 11 mm-long longitudinal surface-breaking toe cracks in ground mild steel welds. A lift-off distance of <1 mm was controlled using a proximity laser and a z-direction motor module to autonomously control the probe lift-off and conform to sample geometry. This study found that an applied magnetic field with a frequency of 800 Hz and a field strength of 10 mT RMS was optimal under the constraint of power consumption, based on the ratio of MFL responses from the two flaws and the weld. It was found that other frequency field combinations had comparable or higher detection but were discounted as they had substantially higher power consumption.

Numerical Study of Steady Flow Past a Sphere in an Aligned Magnetic Field

2004 ◽  
Vol 4 (2) ◽  
pp. 215-227 ◽  
Author(s):  
T.V.S. Sekhar ◽  
R. Sivakumar ◽  
Harish Kumar
Keyword(s):  
Magnetic Field ◽  
Drag Coefficient ◽  
Numerical Study ◽  
Perturbation Parameter ◽  
Accurate Solution ◽  
Defect Correction ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
Aligned Magnetic Field ◽  
Flow Past A Sphere

AbstractThe flow of a steady, incompressible, viscous, electrically conducting fluid past a sphere in the presence of uniform magnetic field parallel to the undisturbed flow is investigated using the finite difference method. The multigrid method with a defect correction (DC) technique is used to achieve the second order accurate solution. The Hartmann number M is used as the perturbation parameter. It has been found that the increase of magnetic field decreases the wake length (L) and increases the drag coefficient. The graphs of streamlines, vorticity lines, drag coefficient, wake length, surface pressure and surface vorticity are presented and discussed

A new wastewater treatment system recovering magnetically immobilized microorganisms under strong magnetic field

2004 ◽  
Vol 4 (1) ◽  
pp. 47-54
Author(s):  
H. Ozaki ◽  
S. Kurinobu ◽  
T. Watanabe ◽  
S. Nishijima ◽  
T. Sumino
Keyword(s):  
Magnetic Field ◽  
Wastewater Treatment ◽  
Magnetic Particles ◽  
High Efficiency ◽  
Nitrifying Bacteria ◽  
Water And Wastewater Treatment ◽  
Magnetic Separator ◽  
Gel Particles ◽  
Water And Wastewater ◽  
Immobilized Microorganisms

A new generation of high gradient magnetic separation (HGMS) has recently received attention again, especially for its applications in the field of water and wastewater treatment. The reason for this attention is that a newly developed superconducting magnet can be used to easily generate a high magnetic field, under which even weakly paramagnetic materials can be separated at high efficiency. We have developed a new wastewater treatment process using magnetic gel particles containing immobilized microorganisms and magnetic particles. The magnetic gel particles are separated and recovered from the effluent in water and wastewater treatment processes, and are then recycled to a bioreactor directly or reused after storing. In this research, a novel type of magnetic separator without a filter matrix was designed for the separation and recovery of magnetic gel particles with different magnetic characteristics. No backwashing is required for this new type of separator. By using the separator, polyethylene glycol (PEG) gel particles with 2% magnetite were continuously separated and recovered from the PEG gel particles with 0.04% magnetite at an efficiency of around 90%. The PEG gel particles containing nitrifying bacteria and magnetic particles were available for the oxidation of ammonia solution at a slightly lower nitrification rate than the PEG gel particles with nitrifying bacteria but without magnetite.

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,...

Study of Finishing Internal Surface Using Magnetic Force Generated by Rotating Magnetic Field in Electromotor

2007 ◽  
Vol 359-360 ◽  
pp. 295-299
Author(s):  
Xin Gai Yao ◽  
Shi Ying Wang ◽  
Yan Hong Ding ◽  
Gang Ya ◽  
Jie Zhang
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Magnetic Particles ◽  
Internal Surface ◽  
Rotating Magnetic Field ◽  
New Method ◽  
Experimental Investigations ◽  
Optimal Value ◽  
Prospective Application ◽  
Tube Type

In the paper, a new method of using rotating magnetic field generated by a stator of alternative electromotor to polish the inner surface of tube-type workpieces is proposed; a finishing device using the stator construction and inverter is designed; the finishing mechanism is analyzed and experiments are carried out. Experimental investigations show that filling amount of magnetic abrasive influences the surface roughness of workpiece directly and have an optimal value. The higher magnetic conductivity is, and the finer finishing effect is. The attraction force of magnetic particles depends on intensity of magnetic induction directly and has the optimal value. The higher the rotation speed is, and the lower the value of surface roughness. Under the optimal experimental condition, the new method can reduce the value of surface roughness more than 2 grades. Therefore, this technique has prospective application future.

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