Effect of magnetic field on natural convection inside a partially-heated vertical duct: Experimental study

Kaneda, Masayuki; Nazato, Kensuke; Fujiwara, Hiroaki; Wada, Kengo; Suga, Kazuhiko

doi:10.1016/j.ijheatmasstransfer.2018.12.056

Cited by 11 publications

(11 citation statements)

References 23 publications

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“…The additional external force applied on the working is the magnetothermal force, thus the effect of the force on the heat and fluid flow is discussed in Figure 5. As Figure 3 suggested, Figure 5a shows a strong ∇b 2 induced near the magnet junction toward the magnet as reported by our group [20]. As suggested in Equation 7, the magnetothermal force is resulted from the multiplication of ∇b 2 and temperature difference.…”

Section: Heat and Fluid Flow With And Without Magnetic Fieldsupporting

confidence: 75%

“…In the literature, the heat transfer can locally enhance and suppress the natural convection near the magnet edge. This phenomenon has also been found by their experiment [20]. Besides, it reported that two magnets paired by alternate poles can induce a remarkable magnetic force at its junction in the normal direction to the magnet.…”

Section: Introductionsupporting

confidence: 73%

“…The Prandtl number is fixed at 13.0 which corresponds to the gadolinium nitrate aqueous solution of 15.5 wt. % which is the same fluid of [20]. The Rayleigh number is fixed at 10 4 which corresponds to the temperature difference ∆T of 0.415 K when the gap between hot and cold is presumed at 10 mm.…”

Section: Of 11mentioning

confidence: 99%

“…These symmetric results are not only by the symmetry of the magnetic force but also the direction of the gravity force. When the gravity is normal to the dominant magnetic force, the combined convection due to gravitational and magnetic forces is no longer symmetric [19,20]. The additional external force applied on the working is the magnetothermal force, thus the effect of the force on the heat and fluid flow is discussed in Figure 5.…”

Section: Heat and Fluid Flow With And Without Magnetic Fieldmentioning

confidence: 99%

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Rayleigh-Bénard Convection of Paramagnetic Liquid under a Magnetic Field from Permanent Magnets

2020

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The convection control is important in terms of the heat transfer enhancement and improvement of the applied devices and resultant products. In this study, the convection control by a magnetic field from block permanent magnets is numerically investigated on the Rayleigh-Bénard convection of paramagnetic fluid. To enhance the magnetic force from the available permanent magnets, pairs of alternating-pole magnets are employed and aligned near the bottom heated wall. The lattice Boltzmann method is employed for the computation of the heat and fluid flow with the consideration of buoyancy and magnetothermal force on the working fluid. It is found that, since the magnetic force at the junction of pair magnets becomes strong remarkably and in the same direction as the gravity, descending convection flow is locally enhanced and the pair of symmetrical roll cells near the magnet junction becomes longitudinal. The local heat transfer corresponds to the affected roll cell pattern; locally enhanced at the magnet junctions and low heat transfer area is shifted aside the magnet outer edge. The averaged Nusselt number on the hot wall also increases proportionally to the magnetic induction but it is saturated at high magnetic induction. This suggests the roll cell pattern is no more largely affected at extremely-high magnetic induction.

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Section: Heat and Fluid Flow With And Without Magnetic Fieldsupporting

confidence: 75%

Section: Introductionsupporting

confidence: 73%

Section: Of 11mentioning

confidence: 99%

Section: Heat and Fluid Flow With And Without Magnetic Fieldmentioning

confidence: 99%

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Rayleigh-Bénard Convection of Paramagnetic Liquid under a Magnetic Field from Permanent Magnets

2020

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“…The available permanent magnets such as neodymium ones have the magnetic induction of 0.5T and more. Although this induction is much smaller than that of the superconducting magnets, authors found by experiment that the natural convection of paramagnetic liquid (gadolinium nitrate hexahydrate aqueous solution, χmm = 120.510 -6 cm 3 /g) can be controlled by a permanent magnet of 573 mT (Kaneda et al, 2019). Additionally, this effect becomes remarkable by employing multiple magnets with opposite orientations.…”

Section: Introductionmentioning

confidence: 99%

Magnetothermal force effect on natural convection through a partially-heated vertical channel

Wada

Fujiwara

Kaneda

et al. 2020

JTST

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Magnetothermal force effect on natural convection through a partially-heated vertical channel Abstract Natural convection of a paramagnetic fluid through a partially-heated vertical channel is numerically studied in the presence of a magnetic field from two block magnets placed behind the heated wall. Magnets are aligned with opposite orientations. This magnet orientation induces strong magnetic force normal to the magnet at the magnet junction due to short distance between poles. When the temperature-dependent magnetic susceptibility changes due to wall heating near the magnet, the magnetothermal force is induced remarkably near the magnet junction. This additional force overlaps to the natural convection along the heated wall and results in the changes of heat and fluid flow along the heated wall. It is found that, flow becomes slow and the local heat transfer is suppressed below the elevation of the magnet junction, and the flow acceleration and heat transfer enhancement are observed above the junction elevation, of which effects depend on the relative magnet elevation to the heated wall. It is also found that the transition to vibrating flow occurs at the specific magnet elevation. The timeaveraged Nusselt number suggests this vibrating convection has the potential to enhance the heat transfer remarkably because this magnetically-induced flow vibration continues along the heated wall up to the outlet.

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Review of interdisciplinary heat transfer enhancement technology for nuclear reactor

Lu¹,

Liu²,

Deng³

et al. 2021

Annals of Nuclear Energy

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Effect of magnetic field on natural convection inside a partially-heated vertical duct: Experimental study

Cited by 11 publications

References 23 publications

Rayleigh-Bénard Convection of Paramagnetic Liquid under a Magnetic Field from Permanent Magnets

Rayleigh-Bénard Convection of Paramagnetic Liquid under a Magnetic Field from Permanent Magnets

Magnetothermal force effect on natural convection through a partially-heated vertical channel

Review of interdisciplinary heat transfer enhancement technology for nuclear reactor

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