The static (buildup) model of particle accumulation on single wires in high gradient magnetic separation: Experimental confirmation

Nesset, Jan E.; Finch, J.A.

doi:10.1109/tmag.1981.1061242

Cited by 34 publications

(8 citation statements)

References 5 publications

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“…The time steps are chosen so that at each step the maximum increment in buildup thickness is equal to one‐tenth of the wire radius. The buildup shapes obtained are very similar to those observed experimentally with weakly paramagnetic particles 20, 23…”

Section: Resultssupporting

confidence: 84%

“…Formation of a single on‐axis spike has been observed experimentally when strongly magnetic particles are used (Fe 3 O 4 ) 23. The static particle buildup model developed by Nesset and Finch20 does not allow for this behavior and is, therefore, not applicable to the capture of strongly magnetic particles. In fact, when strongly magnetic particles such as ferromagnetic or superparamagnetic particles are used, the buildup is itself a magnet and this distorts the original field.…”

Section: Resultsmentioning

confidence: 99%

“…A simplified model that is able to predict the maximum particle accumulation on a wire has been developed and tested experimentally by Liu and Oak19 and Nesset and Finch 20. In this model, the interface is assumed to remain cylindrical at all times, and potential flow theory is invoked to obtain the flow field around the wire.…”

Section: Introductionmentioning

confidence: 99%

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A dynamic buildup growth model for magnetic particle accumulation on single wires in high‐gradient magnetic separation

2011

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in Wiley Online Library (wileyonlinelibrary.com).Magnetic fluids containing nano or submicron magnetic particles and their applications to food, biological, and pharmaceutical systems have recently attracted considerable attention. Magnetic particles can be collected efficiently in magnetizable matrices (e.g., iron wires) in high-gradient magnetic separation processes. However, capture efficiencies based on results for clean, particle-free, wires may be seriously in error because the particle accumulation on the wire distorts the flow and the magnetic fields, and thus influences the capture efficiency. A model is developed here in which the dynamic growth process is treated as a moving boundary problem, with the growing front tracked explicitly by marker points distributed evenly over its surface. The flow field and magnetic field are calculated using a finite element method, and a particle trajectory model is used to calculate the deposition flux on the surface. The marker point distribution and the buildup shape are updated at each simulation step. Simulation results show that, for weakly magnetic particles, the accumulation exhibits a smoothly growing front, whereas for strongly magnetic particles, an instability occurs, leading to dendritic growth. The capture efficiency decreases dramatically as particle accumulation increases; and this trend is more prominent for the transverse configuration than it is for the longitudinal configuration. The simulation results show good agreement with experimental results from the literature.

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Section: Resultssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

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A dynamic buildup growth model for magnetic particle accumulation on single wires in high‐gradient magnetic separation

2011

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“…(b) Stability and Limits of MMPs Deposit in a Blood Vessel. The stability and limit of the MMPs deposit in blood vessels under the presence of a magnetized ferromagnetic wire was simulated by modeling at equilibrium the forces acting on the MMPs (25).…”

Section: Modeling and Simulationmentioning

confidence: 99%

Simulating the Embolization of Blood Vessels Using Magnetic Microparticles and Acupuncture Needle in a Magnetic Field

Rotariu

Iacob

Strachan

et al. 2008

Biotechnol Progress

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Computer models were developed to simulate the capture and subsequent deposition of magnetic microparticles (MMPs) in a blood vessel adjacent to a ferromagnetic wire (e.g., acupuncture needle) magnetized by a uniform external magnetic field. Process parameter conditions were obtained to enable optimal capture of MMPs into the deposit. It was found that the maximum capture distance of the MMPs was within 0.5-2.0 mm when the particles were superparamagnetic and had large size (>1.0 microm) and relative large flow rates (2.5-5.0 cm/s) as in a healthy artery. It was also found that the deposits were asymmetrical and that their size was between 1.0 and 2.0 mm. For the case of lower flow rates as can be found in a tumor (<1.0 mm/s) and using small magnetite particles (0.25-2.0 microm) the maximum capture distance was larger, ranging between approximately 0.5 and 6.4 mm, depending on the blood flow rate, the radius of wire, and particle clustering. The range of embolization (deposition) in this later case was between 0.5 and 5.9 mm. The potential of this technique to generate MMPs deposits to embolize blood vessels inhibiting the blood supply and thus facilitating necrosis of tumors located deep within the patient (3-7 cm) is discussed.

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“…These trajectory models can be used to predict the limiting trajectory (or critical radius) of particles and then calculate the removal efficiency of magnetic filtration; however, they are limited to clean filters. Luborsky and Drummond (24), Nesset and Finch (25,26), and Nesset et al (27) developed models to describe the particle build-up process and the loading conditions of the wires. In the build-up models, it is assumed that particles have uniform size and magnetic susceptibility.…”

Section: Introductionmentioning

confidence: 99%

Magnetic-Seeding Filtration*

Ying

Chin

et al. 1999

Separation Science and Technology

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DISCLAIMERABSTRACT Magnetic-seeding filtration consists of two steps: heterogeneous particle flocculation of magnetic and nonmagnetic particles in a stirred tank and high-gradient magnetic filtration (HGMF). The effects of various parameters affectipg magneticseeding filtration are theoretically and experimentally investigated. A trajectory model that includes hydrodynamic resistance, van der Waals, and electrostatic forces is developed to calculate the flocculation frequency in a turbulent-shear regime. Fractal dimension is introduced to simulate the open structure of aggregates. A magneticfiltration model that consists of trajectory analysis, a particle build-up model, a breakthrough model, and a bivariate population-balance model is developed to predict the breakthrough curve of magnetic-seeding filtration. A good agreement between modeling results and experimental data is obtained. The results show that the model developed in this study can be used to predict the performance of magnetic-seeding filtration without using empirical coefficients or fitting parameters.

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The static (buildup) model of particle accumulation on single wires in high gradient magnetic separation: Experimental confirmation

Cited by 34 publications

References 5 publications

A dynamic buildup growth model for magnetic particle accumulation on single wires in high‐gradient magnetic separation

A dynamic buildup growth model for magnetic particle accumulation on single wires in high‐gradient magnetic separation

Simulating the Embolization of Blood Vessels Using Magnetic Microparticles and Acupuncture Needle in a Magnetic Field

Magnetic-Seeding Filtration*

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