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Hiroyuki Ozoe - One of the best experts on this subject based on the ideXlab platform.

  • EFFECTS OF GRADIENT MAGNETIC FIELDS ON THE MAGNETO-THERMAL MIXED CONVECTION OF AIR IN A HORIZONTAL PIPE
    Chemical Engineering Communications, 2008
    Co-Authors: Hiroyuki Ozoe
    Abstract:

    Effects of gradient magnetic fields on the mixed convection of air in a gravity field are numerically studied with 3-D model equations. The detailed characteristics of the magneto-thermal wind in a pipe are computed for the length ratios L (pipe length divided by pipe diameter) of 20, 30, 62, and 100, with diameter ratios N (diameter of an Electric Coil versus that of the pipe) from 2 to 200. It is found that there exists a best diameter ratio N to maximize the airflow rate for a channel with a fixed length. Detailed flow and temperature profiles are graphically presented for various values of N.

  • Numerical Investigation of Natural Convection in an Enclosure Filled with Porous Medium Under Magnetic Field
    Numerical Heat Transfer Part A: Applications, 2007
    Co-Authors: Min Zeng, Qiuwang Wang, Gang Wang, Zipeng Huang, Hiroyuki Ozoe
    Abstract:

    In this study, natural convection in an enclosure filled with a fluid-saturated porous medium in a strong magnetic field is investigated numerically. Two physical models are considered. One is heated from the bottom and cooled from the top (Model A), and the other is heated from the left side vertical wall and cooled from the opposite wall (Model B). An Electric Coil is set below this enclosure to generate a magnetic field. The Brinkman-Forchheimer extended Darcy model is used to solve the momentum equations, and the energy equations for the fluid and solid are solved with the local thermal nonequilibrium (LTNE) model. The linkage between velocity and pressure is handled with the SIMPLE algorithm. Computations are performed for a range of Darcy number from 10−5 to 10−1, Rayleigh number from 103 to 105, and magnetic force parameter γ from 0 to 100. The results show that the magnetic force has significant effect on the flow field and heat transfer in the fluid-saturated porous medium.

  • Numerical investigation of natural convection in an inclined enclosure filled with porous medium under magnetic field
    International Journal of Heat and Mass Transfer, 2007
    Co-Authors: Qiuwang Wang, Min Zeng, Zhu Huang, Gang Wang, Hiroyuki Ozoe
    Abstract:

    Abstract In the present study, natural convection of fluid in an inclined enclosure filled with porous medium is numerically investigated in a strong magnetic field. The physical model is heated from left-hand side vertical wall and cooled from opposing wall. Above this enclosure an Electric Coil is set to generate a magnetic field. The Brinkman–Forchheimer extended Darcy model is used to solve the momentum equations, and the energy equations for fluid and solid are solved with the local thermal non-equilibrium (LTNE) models. Computations are performed for a range of the Darcy number from 10 −5 to 10 −1 , the inclination angle from 0 to π/2, and magnetic force parameter γ from 0 to 100. The results show that both the magnetic force and the inclination angle have significant effect on the flow field and heat transfer in porous medium.

  • Application of multiple magnetic Coils to drive the air flow in a long pipe
    International Journal of Heat and Mass Transfer, 2006
    Co-Authors: Hiroyuki Ozoe
    Abstract:

    Abstract The laminar air flow in a pipe is studied with application of multiple magnetic fields at the point of uniform heat flux heating from the wall as the first boundary conditions. As the second boundary condition, after a Coil, uniform heat flux heating and then uniform heat flux cooling from the wall is applied. Numerical computations are successfully carried out by solving transient 2-D equations with pressure gradient boundary condition for three lengths of pipe and two boundary conditions. The first one is for a ratio of pipe length and diameter L = 10 with a single Electric Coil. The second one is for L = 20 with two Electric Coils and the third one is for L = 30 with three Electric Coils to generate the magnetic field. A parameter ξ is from 0 to 2 × 107, which represents the strength of the magnetic field and the uniform heat flux from the pipe wall. The results show that the volume flow rate increases with the strength of magnetic field. Magnetic fields generated by the multi-Coils can drive the air flow in the corresponding longer pipe almost equally to the shorter one with a single Coil. From the distributions of the cross-sectional magnetic force along the pipe length, the effect of pressure, pressure gradient distribution along the pipe length, and the effect of gradient magnetic field and temperature field on the overall air flow rate can be analyzed and compared on the effect of wall cooling.

  • HEAT TRANSFER CONTROL IN QUIESCENT AIR WITH THERMAL GRADIENT BY MAGNETIZING FORCE UNDER BOTH GRAVITATIONAL AND NONGRAVITATIONAL FIELDS
    Numerical Heat Transfer Part A: Applications, 2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    ABSTRACT Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force on quiescent air with thermal gradient in a vertical cylindrical container under both gravitational and nongravitational fields. Several sizes and axial positions of a circular Electric Coil were tested so that the magnetizing force depended on the magnetic gradient. Under both gravitational and nongravitational fields, the convection was induced in quiescent air with thermal gradient by the magnetizing force; however, flow pattern and Nusselt number depended strongly on the size and the axial position of the circular Electric Coil in addition to the magnetic strength.

Masato Akamatsu - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Computation on Magnetothermal Air Jet in Gravitational and Nongravitational Fields
    Annals of the New York Academy of Sciences, 2006
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Hitoshi Ogasawara
    Abstract:

    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.

  • HEAT TRANSFER CONTROL IN QUIESCENT AIR WITH THERMAL GRADIENT BY MAGNETIZING FORCE UNDER BOTH GRAVITATIONAL AND NONGRAVITATIONAL FIELDS
    Numerical Heat Transfer Part A: Applications, 2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    ABSTRACT Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force on quiescent air with thermal gradient in a vertical cylindrical container under both gravitational and nongravitational fields. Several sizes and axial positions of a circular Electric Coil were tested so that the magnetizing force depended on the magnetic gradient. Under both gravitational and nongravitational fields, the convection was induced in quiescent air with thermal gradient by the magnetizing force; however, flow pattern and Nusselt number depended strongly on the size and the axial position of the circular Electric Coil in addition to the magnetic strength.

  • Aerial flow in a vertical cylindrical container with thermal gradient under a vertical magnetic field
    Progress in Computational Fluid Dynamics An International Journal, 2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Hiroyuki Ozoe
    Abstract:

    This study focuses on how magnetising force affects the convection of air in a vertical cylindrical container with thermal and magnetic field gradients in non-gravitational and gravitational fields. The model systems with three different thermal boundary conditions are considered in the present work and numerical computations were carried out by changing the relative location of an Electric Coil and container. In a non-gravitational field, the aerial flow was induced by the magnetising force. On the other hand, in a gravitational field, the air was driven by both gravitational and magnetising forces. In both fields, flow pattern and heat transfer rate greatly depended on the axial location of the Electric Coil. Under the specific numerical condition, the pulsating flow was observed by the coupling of gravitational and magnetising forces. These phenomena could be successfully explained by visualising the field of magnetising force and considering the mass magnetic susceptibility of air according to Curie's law.

  • Numerical computation of magnetothermal convection of water in a vertical cylindrical enclosure
    2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    Numerical computations were carried out to clarify the effect of Kelvin force on the flow of water in a vertical cylindrical enclosure heated from below and cooled from above under a vertical magnetic field gradient. Since the Kelvin force that is produced by the magnetic field gradient depends on the position and the size of a circular Electric Coil, the Coil was placed at either the hot or the cold plate and the Coil diameter was set to be 2.5 or 5 times that of the enclosure. First, to understand the mechanism of the generation of the magnetothermal convection induced by the Kelvin force alone, the transition of velocity and temperature fields were visualized under a non-gravitational field

  • The Control of Aerial Flow by the Magnetizing Force
    Heat Transfer Volume 3, 2003
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force for air in a vertical cylindrical container with the thermal and magnetic field gradients under gravitational and non-gravitational fields. Several axial position of the Electric Coil was tested for numerical computation. In a vertical cylindrical container with the stagnant conduction and the Benard conditions, the aerial flow was able to be controlled by the magnetizing force under both gravitational and non-gravitational fields. The flow pattern and the heat transfer rate strongly depended on the axial position of the Electric Coil.Copyright © 2003 by ASME

Mitsuo Higano - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Computation on Magnetothermal Air Jet in Gravitational and Nongravitational Fields
    Annals of the New York Academy of Sciences, 2006
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Hitoshi Ogasawara
    Abstract:

    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.

  • HEAT TRANSFER CONTROL IN QUIESCENT AIR WITH THERMAL GRADIENT BY MAGNETIZING FORCE UNDER BOTH GRAVITATIONAL AND NONGRAVITATIONAL FIELDS
    Numerical Heat Transfer Part A: Applications, 2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    ABSTRACT Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force on quiescent air with thermal gradient in a vertical cylindrical container under both gravitational and nongravitational fields. Several sizes and axial positions of a circular Electric Coil were tested so that the magnetizing force depended on the magnetic gradient. Under both gravitational and nongravitational fields, the convection was induced in quiescent air with thermal gradient by the magnetizing force; however, flow pattern and Nusselt number depended strongly on the size and the axial position of the circular Electric Coil in addition to the magnetic strength.

  • Aerial flow in a vertical cylindrical container with thermal gradient under a vertical magnetic field
    Progress in Computational Fluid Dynamics An International Journal, 2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Hiroyuki Ozoe
    Abstract:

    This study focuses on how magnetising force affects the convection of air in a vertical cylindrical container with thermal and magnetic field gradients in non-gravitational and gravitational fields. The model systems with three different thermal boundary conditions are considered in the present work and numerical computations were carried out by changing the relative location of an Electric Coil and container. In a non-gravitational field, the aerial flow was induced by the magnetising force. On the other hand, in a gravitational field, the air was driven by both gravitational and magnetising forces. In both fields, flow pattern and heat transfer rate greatly depended on the axial location of the Electric Coil. Under the specific numerical condition, the pulsating flow was observed by the coupling of gravitational and magnetising forces. These phenomena could be successfully explained by visualising the field of magnetising force and considering the mass magnetic susceptibility of air according to Curie's law.

  • Numerical computation of magnetothermal convection of water in a vertical cylindrical enclosure
    2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    Numerical computations were carried out to clarify the effect of Kelvin force on the flow of water in a vertical cylindrical enclosure heated from below and cooled from above under a vertical magnetic field gradient. Since the Kelvin force that is produced by the magnetic field gradient depends on the position and the size of a circular Electric Coil, the Coil was placed at either the hot or the cold plate and the Coil diameter was set to be 2.5 or 5 times that of the enclosure. First, to understand the mechanism of the generation of the magnetothermal convection induced by the Kelvin force alone, the transition of velocity and temperature fields were visualized under a non-gravitational field

  • The Control of Aerial Flow by the Magnetizing Force
    Heat Transfer Volume 3, 2003
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force for air in a vertical cylindrical container with the thermal and magnetic field gradients under gravitational and non-gravitational fields. Several axial position of the Electric Coil was tested for numerical computation. In a vertical cylindrical container with the stagnant conduction and the Benard conditions, the aerial flow was able to be controlled by the magnetizing force under both gravitational and non-gravitational fields. The flow pattern and the heat transfer rate strongly depended on the axial position of the Electric Coil.Copyright © 2003 by ASME

Yoshio Takahashi - One of the best experts on this subject based on the ideXlab platform.

  • HEAT TRANSFER CONTROL IN QUIESCENT AIR WITH THERMAL GRADIENT BY MAGNETIZING FORCE UNDER BOTH GRAVITATIONAL AND NONGRAVITATIONAL FIELDS
    Numerical Heat Transfer Part A: Applications, 2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    ABSTRACT Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force on quiescent air with thermal gradient in a vertical cylindrical container under both gravitational and nongravitational fields. Several sizes and axial positions of a circular Electric Coil were tested so that the magnetizing force depended on the magnetic gradient. Under both gravitational and nongravitational fields, the convection was induced in quiescent air with thermal gradient by the magnetizing force; however, flow pattern and Nusselt number depended strongly on the size and the axial position of the circular Electric Coil in addition to the magnetic strength.

  • Numerical computation of magnetothermal convection of water in a vertical cylindrical enclosure
    2005
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    Numerical computations were carried out to clarify the effect of Kelvin force on the flow of water in a vertical cylindrical enclosure heated from below and cooled from above under a vertical magnetic field gradient. Since the Kelvin force that is produced by the magnetic field gradient depends on the position and the size of a circular Electric Coil, the Coil was placed at either the hot or the cold plate and the Coil diameter was set to be 2.5 or 5 times that of the enclosure. First, to understand the mechanism of the generation of the magnetothermal convection induced by the Kelvin force alone, the transition of velocity and temperature fields were visualized under a non-gravitational field

  • The Control of Aerial Flow by the Magnetizing Force
    Heat Transfer Volume 3, 2003
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force for air in a vertical cylindrical container with the thermal and magnetic field gradients under gravitational and non-gravitational fields. Several axial position of the Electric Coil was tested for numerical computation. In a vertical cylindrical container with the stagnant conduction and the Benard conditions, the aerial flow was able to be controlled by the magnetizing force under both gravitational and non-gravitational fields. The flow pattern and the heat transfer rate strongly depended on the axial position of the Electric Coil.Copyright © 2003 by ASME

  • Numerical Analysis of Air Convection in a Vertical Cylindrical Container With and Without a Gravitational Field Under a Gradient of a Magnetic Field
    Computational Technologies for Fluid Thermal Structural Chemical Systems With Industrial Applications Volume 1, 2002
    Co-Authors: Masato Akamatsu, Mitsuo Higano, Yoshio Takahashi, Hiroyuki Ozoe
    Abstract:

    Two-dimensional numerical computations were carried out for natural convection of air in a vertical cylindrical container with and without a gravitational field under a gradient of a magnetic field. The magnetic field and the magnetizing force were induced in the cylinder area and the strength and the vectors of the magnetizing force were dependent on the axial location of the Electric Coil. Sample computations were carried out by changing the relative orientation of an Electric Coil and container. In a gravitational field, air in a cylindrical container was driven by both gravitational and magnetizing forces. On the other hand, the air flow was induced by the magnetizing force even in a non-gravitational field. Flow pattern and the heat transfer rate greatly depended on the axial position of the Electric Coil under both gravitational and non-gravitational fields.Copyright © 2002 by ASME

Masayuki Kaneda - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic Convection Inside a Polymer Solution Droplet on a Lyophobic Surface
    Numerical Heat Transfer Part A: Applications, 2011
    Co-Authors: Masayuki Kaneda, Yusuke Matsushima, Kazuhiko Suga
    Abstract:

    Convection inside a polymer solution sessile droplet under a strong magnetic field is numerically studied. The droplet presumed is a diamagnetism solution, which has different magnetic susceptibility between solute and solvent. The magnetic field is presumed by a single Electric Coil. The Coil placed in a lower position induces the upward force near the surface, which enhances the Marangoni convection. If the Coil is located above the droplet, the flow is suppressed by the downward force. These effects are found to be remarkable for a large droplet.

  • Convection of air in a cubic enclosure with an Electric Coil inclined in general orientations
    Fluid Dynamics Research, 2005
    Co-Authors: Tomasz Bednarz, Hiroyuki Ozoe, Toshio Tagawa, Masayuki Kaneda, Janusz S. Szmyd
    Abstract:

    Abstract Three-dimensional numerical calculations are carried out for the convection of air in a cubic enclosure under both magnetizing and gravitational fields. The magnetic field is generated by the Electric current flowing through a single circular Coil which is placed around the enclosure with its center at the center of the cube. The Electric Coil can be inclined in any orientation by two inclination angles: φ y and φ z . Computations are carried out for the whole range of both angles and for Pr = 0.71 , Ra = 1.51 × 10 4 , 9.06 × 10 4 , and γ = 10 , 30, 60 and 100, where Pr is the Prandtl number, Ra is the Rayleigh number and γ is the strength of the magnetizing force. The maximum values of the heat transfer rate were obtained at φ z = π / 2 and the minimum at φ z = 0 for appropriate values of φ y . The present work shows the possibility of controlling the heat transfer rate using a magnetic field.

  • Three-dimensional numerical computation for magnetic convection of air inside a cylinder heated and cooled isothermally from a side wall
    International Journal of Heat and Mass Transfer, 2005
    Co-Authors: Piotr Filar, Hiroyuki Ozoe, Toshio Tagawa, Masayuki Kaneda, Elzbieta Fornalik, Janusz S. Szmyd
    Abstract:

    Abstract Three-dimensional convection of air in a vertical cylinder isothermally heated and cooled from a side wall was numerically computed both in magnetic and gravity fields. A single Electric Coil was placed around a cylinder to generate a magnetic field. Convection was calculated for various Coil levels and magnetic strengths. The gravity field, magnetic strength and Rayleigh number are shown to have substantial effect. Convection modes and heat transfer rates are also presented.

  • Numerical study of joint magnetisation and gravitational convection of air in a cubic enclosure with an inclined Electric Coil
    Progress in Computational Fluid Dynamics An International Journal, 2005
    Co-Authors: Tomasz Bednarz, Hiroyuki Ozoe, Toshio Tagawa, Masayuki Kaneda, Janusz S. Szmyd
    Abstract:

    Numerical computations were carried out for thermal convection of air in a cubic enclosure under both magnetising and gravitational fields. A one-turned circular Coil with Electric current, which induces a magnetic field, was placed around the enclosure and inclined with its plane oblique to the hot and cold walls and with its centre at the centre of enclosure. Computations were carried out for several combinations of parameters: Pr = 0.71; Ra = 1.51 × 104, 9.06 × 104; γ = 10, 30, 60, 100; γeuler from - π/2 to π/2.

  • AIR CONVECTION IN A CUBIC ENCLOSURE WITH LATERALLY SHIFTED Electric Coil WITHOUT A GRAVITY FIELD
    2004
    Co-Authors: Tomasz Bednarz, Toshio Tagawa, Masayuki Kaneda, Hiroyuki Ozoe
    Abstract:

    m h- The boundary conditions are: at τ < 0, initial condition is a heat conduction state: U = V = W = 0, T = −X (−0.5 ≤ X ≤ 0.5), at the left-hand side vertical wall: T = 0.5, at the right-hand side vertical wall: T = −0.5, at the vertical adiabatic walls: ∂T/∂Y = 0, at the horizontal adiabatic walls: ∂T/∂Z = 0, at all walls: U = V = W = 0. These dimensionless equations were approximated by finite difference equations and numerically solved with the HSMAC (2) scheme for a staggered mesh system. The number of meshes is 40×40×40. Distribution of the magnetic field was calculated using Biot-Savart's law. MODEL SYSTEM AND COMPUTED RESULTS Model system is shown in Figure 1. The cubic enclosure which is heated isothermally from one vertical wall and cooled from opposite one and with other four walls thermally insulated is considered to be placed in a bore space of a superconducting magnet. In our numerical computations the magnetic field is generated by a single Electric Coil which is placed in a horizontal plane at various elevations Zc and further shifted in the X direction at Xc. The magnetic buoyancy force which drives the fluid has been known to be proportional to the gradient of the square of the magnetic induction and is determined by the magnitude of the Electric current flowing through the Coil but not the current direction. In the present computations the dimensional combinations are as follows: the length of the cubic enclosure is set as 0.032(m) and the diameter of the Electric Coil as 0.1(m).