Mesoscopic structuring and yield stress of magnetofluidized fine particles

Valverde, José Manuel; Espin, M. J.; Quintanilla, M. A. S.; Castellanos, A.

doi:10.1209/0295-5075/88/24003

Cited by 2 publications

(4 citation statements)

References 11 publications

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“…When the universal van der Waals force becomes much larger than particle weight, natural aggregates may form large-scale branched structures when magnetized by an external field, which may represent an additional contribution to the increase of the yield stress of the co-flow field-stabilized bed. Magnetic aggregation coupled with natural aggregation was observed to play a remarkable role on a fine powder where most of particles were naturally aggregated …”

Section: Visualization Of the Magnetofluidized Bed Structurementioning

confidence: 99%

“…Magnetic aggregation coupled with natural aggregation was observed to play a remarkable role on a fine powder where most of particles were naturally aggregated. 10…”

Section: Visualization Of the Magnetofluidized Bed Structurementioning

confidence: 99%

“…In the case of powders with a high level of particle size polydispersion, the natural aggregation of the fine particles due to van der Waals forces favored the formation of large-scale branched structures in the MFB, which increased the yield stress and favored stabilization at large values of the gas velocity. 10 Further experimental results on the yield stress of magnetically stabilized beds in the cross-flow field configuration and operated in the magnetization LAST mode demonstrated that the yield stress was enhanced, and it increased with the field strength at an appreciably higher rate, as the particle size was increased. 11 It was argued that the yield stress was critically influenced by the microstructure of the stabilized bed subjected to a small consolidation.…”

Section: Introductionmentioning

confidence: 96%

“…In order to better understand the role of interparticle contact forces on magnetic stabilization, measurements on the yield stress of MFBs, as a function of the intervening physical parameters and conditions, would provide useful information to be incorporated on stability models. Experimental measurements on the yield stress and transition to stability of MFBs subjected to a cross-flow magnetic field have been recently reported. ,− These works showed that field operation mode and particle size distribution can be relevant parameters on magnetic stabilization. Application of the field to a naturally stabilized bed, wherein particles were held in enduring positions and were not allowed rearranging, did not cause an appreciable increment of the yield stress.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Particle Size and Field Orientation on the Yield Stress of Magnetostabilized Fluidized Beds

Valverde

Quintanilla

Espin

2012

Ind. Eng. Chem. Res.

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In this work, we present experimental measurements of the yield stress of gas-fluidized beds of magnetizable particles stabilized by an externally imposed magnetic field. Powder samples consist of spherical magnetite particles 35–65 μm in size. The magnetic field is applied in the bubbling regime and the gas velocity is decreased. At a critical gas velocity, particle chains that have formed due to attractive magnetostatic forces become jammed and the bed transits to a solidlike expanded state with a non-negligible yield stress. Our experimental setup allows us for taking measurements of the yield stress of the bed stabilized by a magnetic field oriented either in the vertical or horizontal direction (co-flow and cross-flow field configurations, respectively). In the cross-flow field configuration, the magnetic yield stress is increased with particle size. On the other hand, the magnetic yield stress is decreased in the co-flow field configuration as particle size is increased. This is interpreted as due to the dependence of the interparticle magnetostatic force on the interparticle contact angle with the field, which is, on average, affected by particle size in the jammed bed subjected to small consolidations.

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Section: Visualization Of the Magnetofluidized Bed Structurementioning

confidence: 99%

“…Magnetic aggregation coupled with natural aggregation was observed to play a remarkable role on a fine powder where most of particles were naturally aggregated. 10…”

Section: Visualization Of the Magnetofluidized Bed Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Particle Size and Field Orientation on the Yield Stress of Magnetostabilized Fluidized Beds

Valverde

Quintanilla

Espin

2012

Ind. Eng. Chem. Res.

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Stabilization of fluidized beds of particles magnetized by an external field: effects of particle size and field orientation

2013

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This paper reports experimental measurements on the yield stress, the permeability to gas flow and the gas velocity at the jamming transition of gas-fluidized beds of magnetizable particles as affected by particle size and orientation and strength of an externally imposed magnetic field. Tested samples consisted of relatively monodisperse magnetite powders of 35, 50 and 65 µm particle size. The permeability to gas flow and jamming transition velocity increase with particle size and in a specially marked way when the magnetic field is applied along the gas flow direction. The magnetic contribution to the yield stress is also particularly enhanced for co-flow magnetic fields. However, the effect of particle size on the yield stress shows a dependence on the microstructure packing as affected by particle size and orientation of the field. The magnetic yield stress increases with particle size for magnetic fields applied in the cross-flow configuration while the opposite trend is observed when the direction of the magnetic field is parallel to the gas flow. The observations reported in this paper are generally explained by the formation of chains of particles due to attractive magnetic forces between the magnetized particles and the orientation of these chains with respect to the magnetic field.

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Mesoscopic structuring and yield stress of magnetofluidized fine particles

Cited by 2 publications

References 11 publications

Effects of Particle Size and Field Orientation on the Yield Stress of Magnetostabilized Fluidized Beds

Effects of Particle Size and Field Orientation on the Yield Stress of Magnetostabilized Fluidized Beds

Stabilization of fluidized beds of particles magnetized by an external field: effects of particle size and field orientation

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