Heat Transfer Control in Quiescent Air With Thermal Gradient by Magnetizing Force Under Both Gravitational and Nongravitational Fields

Akamatsu, Masato; Higano, Mitsuo; Takahashi, Yoshio; Ozoe, Hiroyuki

doi:10.1080/10407780590889176

Cited by 5 publications

(3 citation statements)

References 17 publications

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“…Among recent publications we can find examples on the effect of partition in an enclosure [1,2], heat and flow characteristics for a non-Newtonian fluid [3,4], and various distributions of heat sources [5] or spatial side-wall temperature variations [6]. Furthermore, even the effect of magnetic field has been studied either for electroconducting fluids [7] or for nonelectroconducting fluids [8][9][10]. On the other hand, natural convection related to environmental systems has been studied for many years with oscillating temperature boundary condition for the fluid layer for various systems such as the meteorological environment, architectural room with oscillatory outside temperature, geothermal systems, etc.…”

Section: Introductionmentioning

confidence: 98%

Upward Heat Flux Through the Horizontal Fluid Layer of Water with Sinusoidal Wall Temperature at the Top or Bottom Boundary

Wang

Zeng

et al. 2007

Numerical Heat Transfer, Part A: Applications

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Either top or bottom wall temperature of an infinite horizontal fluid layer at Pr ¼ 6 is sinusoidally oscillated with constant average temperature on the opposing horizontal wall. This is a system with no temperature difference between the top and bottom walls in a timeaveraged sense, as studied by Kalabin et al. for a square channel. The fluid is water, and the Boussinesq approximation is made. The computational region of height 1 and horizontal width 1 is adopted and numerical computation is carried out. The results show that the fluctuating Nusselt numbers computed at both the top and bottom walls give positive timeaveraged values for two different frequencies computed. Time-dependent convection plumes occur when the bottom wall temperature becomes higher than the top wall temperature. The time-averaged heat flux is always positive, i.e., upward, even if the time-averaged temperature difference is zero between the top and bottom walls. This holds even if the oscillating temperature is on either the top or bottom wall. Two periods of temperature oscillation give one period of oscillation in flow and Nu, at least for the parameters studied.

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Section: Introductionmentioning

confidence: 98%

Upward Heat Flux Through the Horizontal Fluid Layer of Water with Sinusoidal Wall Temperature at the Top or Bottom Boundary

Wang

Zeng

et al. 2007

Numerical Heat Transfer, Part A: Applications

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“…As a first research step, in our previous work [23] we simulated numerically the effect of the Kelvin force on quiescent air in a vertical cylindrical enclosure cooled from below and heated from above under a vertical magnetic field gradient. As a second research step, in the present study we used two-dimensional numerical computations to examine the effect of Kelvin force on the Rayleigh-Benard natural convection of air in a vertical cylindrical enclosure heated from below and cooled from above under a vertical magnetic field gradient.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Control of Rayleigh-Benard Natural Convection of Air by Kelvin Force

Akamatsu

Higano

Ozoe

2007

Numerical Heat Transfer, Part A: Applications

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Two-dimensional numerical computations are carried out to clarify the effect of Kelvin force on the Rayleigh-Benard natural convection of air in an enclosure under a magnetic field gradient. The computed results suggest that the Kelvin force could be utilized to control the heat transfer rate and the flow of the Rayleigh-Benard natural convection of air having a paramagnetic property. The transient characteristics of magnetothermal convection induced by the Kelvin force are also examined. Various phenomena caused by the Kelvin force are explained by considering the temperature dependence of the air's mass magnetic susceptibility according to Curie's law.

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“…Following the recent development of a superconducting magnet that does not require liquid helium, numerous studies have been conducted in a wide range of fields-including chemistry, biology, and engineering-to determine the effects of a strong magnetic field on fluids with paramagnetic or diamagnetic properties. [1][2][3][4][5][6][7][8][9][10][11][12][13] These studies have utilized the Kelvin force, 14 which is produced under the gradient of a magnetic field. This force is called a magnetic or magnetizing force in the field of engineering.…”

Section: Introductionmentioning

confidence: 99%

Numerical Computation on Magnetothermal Air Jet in Gravitational and Nongravitational Fields

Akamatsu

Higano

Ogasawara

2006

Annals of the New York Academy of Sciences

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Two-dimensional numerical computations were carried out in order to elucidate the effect of a Kelvin force on the air in two coaxial circular pipes with open ends under both gravitational and nongravitational fields. The outer pipe with open ends corresponds to the bore space of the superconducting magnet. The inner pipe with open ends is assumed to be placed inside this bore space. The sidewall of the outer pipe is cooled isothermally. The central region of the inner pipe is heated isothermally and the other region is thermally insulated. The magnetic gradient that was produced by the electric current circulating within the circular electric coil was applied to air in two coaxial circular pipes with a thermal gradient. Moreover, the present numerical computations were carried out by changing the relative positions of the circular electric coil and the inner pipe. In both gravitational and nongravitational fields, when the circular electric coil was placed at the end of the heated region of the inner pipe, the Kelvin force was produced in the inner pipe and the magnetothermal air jet was created. As a result, the hotter air rapidly flowed out from the end of the inner pipe. These phenomena could be successfully explained by considering the temperature dependence of the mass magnetic susceptibility of air according to Curie's law.

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Heat Transfer Control in Quiescent Air With Thermal Gradient by Magnetizing Force Under Both Gravitational and Nongravitational Fields

Cited by 5 publications

References 17 publications

Upward Heat Flux Through the Horizontal Fluid Layer of Water with Sinusoidal Wall Temperature at the Top or Bottom Boundary

Upward Heat Flux Through the Horizontal Fluid Layer of Water with Sinusoidal Wall Temperature at the Top or Bottom Boundary

Heat Transfer Control of Rayleigh-Benard Natural Convection of Air by Kelvin Force

Numerical Computation on Magnetothermal Air Jet in Gravitational and Nongravitational Fields

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