Natural convection within a vertical finite-length channel in free space

The radiation characteristics of an axially oriented point source of electric current and a filament of finite length with a triangular current distribution are treated for the case in which these sources are situated at the center of an infinite cylindrical column of free space and surrounded by a homogeneous, loss-free magnetoionic medium. The direction of the magnetostatic field is assumed to be parallel to the axis of the free-space column which is an idealization for the geometry of the ion sheath formed around the antenna in the ionosphere. The dependence of the radiation resistance of these sources on the frequency and the ion-sheath thickness is examined. It is found that, within the framework of the classical magnetoionic theory, the radiation resistance of even a point source of electric current remains finite for all frequencies, provided the ion-sheath effects are included. Also the radiation resistance of a finite-length filament with a triangular current distribution is found to be insensitive to the changes in the thickness of the ion sheath. This result is in conformity with the experimental observations, which indicate no data variations correlated with the changes in the thickness of the ion sheath.

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An investigation of a high temperature difference natural convection in a finite length channel without Bossinesq assumption

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2009.01.012 ◽

2009 ◽

Vol 52 (11-12) ◽

pp. 2571-2580 ◽

Cited By ~ 19

Author(s):

Wu-Shung Fu ◽

Chung-Gang Li ◽

Chien-Ping Huang ◽

Jieh-Chau Huang

Keyword(s):

High Temperature ◽

Natural Convection ◽

Finite Length ◽

Temperature Difference

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Transient Natural Convection Between Vertical Finite Length Heated Plates

Journal of Thermophysics and Heat Transfer ◽

10.2514/2.6223 ◽

1997 ◽

Vol 11 (2) ◽

pp. 203-211 ◽

Cited By ~ 7

Author(s):

Kuo-Ping Chang ◽

Ying-Huei Hung

Keyword(s):

Natural Convection ◽

Finite Length ◽

Transient Natural Convection ◽

Heated Plates

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Enhanced Heat Transfer From a Horizontal Finned Tube Situated in a Vertical Channel

Journal of Heat Transfer ◽

10.1115/1.3246906 ◽

1986 ◽

Vol 108 (1) ◽

pp. 62-69 ◽

Cited By ~ 4

Author(s):

E. M. Sparrow ◽

M. A. Ansari ◽

P. C. Stryker ◽

R. Ruiz

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

Free Space ◽

Vertical Channel ◽

Finned Tube ◽

Geometric Parameters ◽

Vertical Position ◽

Heat Transfer Characteristics ◽

Enhanced Heat Transfer ◽

Transfer Rates

Experiments were performed to determine the heat transfer characteristics of a horizontal finned tube situated in a vertical channel which is open to the ambient at the top and bottom. The heat transfer from the finned tube is by natural convection and radiation. The response of the finned-tube heat transfer to three geometric parameters was investigated: (1) the vertical position of the tube in the channel, (2) the clearance between the fin tips and the channel walls, and (3) the height of the channel. Experiments were also carried out with the finned tube situated in free space. It was found that in-channel positioning of the finned tube gave rise to substantially higher heat transfer rates than did free-space positioning. With the finned tube situated in the channel, the heat transfer was enhanced by: (1) positioning the tube at the bottom of the channel, (2) small tip-to-wall clearances, and (3) tall channels.

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