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Journal ArticleDOI

Effect of thick horizontal partial partition attached to one of the active walls of a differentially heated square cavity

01 May 1994-Numerical Heat Transfer Part A-applications (Taylor & Francis Group)-Vol. 25, Iss: 5, pp 611-625
TL;DR: In this paper, the effect of a partial horizontal partition plate of finite thickness attached to the heated vertical wall of a differentially heated square cavity has been studied numerically using the finite element method.
Abstract: The effect of a partial horizontal partition plate of finite thickness, attached to the heated vertical wall of a differentially heated square cavity, has been studied numerically using the finite element method. The partition thickness is varied from 0.5% of the height of the cavity to 10%. The partition is considered to be located at the middle of the hot wall of a width equivalent to 20% of the cavity width. It is observed that as the partition thickness is reduced, heat transfer across the cavity decreases at first, until a critical thickness of the partition plate is reached. Beyond this value, heat transfer increases as the thickness of the partition is further reduced. Streamline maps are found to be notably sensitive to the partition thickness. The effect of conductivity of the partition material on heat transfer is also studied. Except for material with poor thermal properties, conductivity of the partition is observed to have a negligible effect on heat transfer.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors investigated the transition from a steady flow to an unsteady flow induced by an adiabatic fin on the sidewall of a differentially heated cavity using numerical simulation.

33 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a numerical study of the radiation-natural convection interactions in a differentially heated enclosure, within which a centered, squared, heat-conducting body generates heat.
Abstract: In this paper, we present a numerical study of the radiation-natural convection interactions in a differentially heated enclosure, within which a centered, squared, heat-conducting body generates heat. A specifically developed numerical model based on the finite-volume method and the SIMPLER algorithm is used for the solution of the governing equations. The working fluid (air) is perfectly transparent to the radiation. The Rayleigh number Ra and the temperature-difference ratio ΔT* were varied parametrically. For Pr = 0.71, the results obtained show that: (i) The isotherms and streamlines are strongly affected by the radiation exchange at high Rayleigh numbers (Ra ≥ 106), (ii) the temperature of the inner body decreases under the radiation exchange effect, (iii) for a constant Ra, the average Nusselt number at the hot and cold walls (Nuh and Nuc) vary linearly with increasing ΔT*: Nuh decreases with ΔT* while Nuc increases with ΔT*. Furthermore, the radiation exchange increases both average Nusselt numbers Nuh and Nuc, especially at Ra ≥ 105, and consequently, increases.

31 citations

Journal ArticleDOI
TL;DR: In this paper, a cubical enclosure with a thick partition fitted vertically on the hot wall is numerically investigated for Rayleigh numbers of 103-106, and a three dimensional convective circulation is generated, in which the cold flow sweeps the fin faces and hot wall, with low flow blockage.

25 citations

Journal ArticleDOI
TL;DR: In this article, the authors used PSO algorithm to obtain characteristics of very conductive thin fin in the confined cavity, where a pair of coordinates (x, y) is selected for each fin such that y is the position of each fin and x is its size.

23 citations

Journal ArticleDOI
TL;DR: In this paper, the optimal shape of cavity with change of hot walls geometry is obtained using PSO algorithm, where near domain of hot wall is divided into similar blocks as those can either be solid or fluid.

21 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the authors used mesh refnement and extrapolation to obtain an accurate solution of the equations describing two-dimensional natural convection in a square cavity with differentially heated side walls.
Abstract: Details are given of the computational method used to obtain an accurate solution of the equations describing two-dimensional natural convection in a square cavity with differentially heated side walls. Second-order, central difference approximations were used. Mesh refnement and extrapolation led to solutions for 103⩽Ra⩽10 6 which are believed to be accurate to better than 1 per cent at the highest Rayleigh number and down to one-tenth of that at the lowest value.

2,529 citations

Journal ArticleDOI
TL;DR: In this paper, the complex nature of the natural convection phenomena in enclosures is discussed and the boundary value problem is formulated, assuming that the motion is 2D and steady, the fluid is incompressible and frictional heating is negligible, and the difference between the hot wall and cold wall temperatures is small relative to the absolute temperatures of the cold wall.
Abstract: Publisher Summary This chapter discusses the complex nature of the natural convection phenomena in enclosures It discusses the two basic configurations of natural convection— that is, a rectangular cavity and a horizontal circular cylinder In rectangular cavities, consideration is given to the two-dimensional convective motion generated by the buoyancy force on the fluid in a rectangle and to the associated heat transfer The two long sides are vertical boundaries held at different temperatures and the short sides can either be heat conducting or insulated Particular attention is given to the different flow regimes that can occur and the heat transfer across the fluid space between the two plane parallel vertical boundaries Although heat transfer by radiation may not be negligible it is independent of the other types of heat transfer and can be fairly accurately calculated separately To formulate the boundary value problem that describes this phenomena it is assumed that: (a) the motion is two-dimensional and steady, (b) the fluid is incompressible and frictional heating is negligible, and (c) the difference between the hot wall and cold wall temperatures is small relative to the absolute temperatures of the cold wall In horizontal circular cylinder, consideration is given to the large Rayleigh number flow with the Prandtl number large and the Grashof number of unit order of the magnitude

973 citations

Journal ArticleDOI
TL;DR: In this article, the boundary layer solution predicting the heat transfer rate is derived on the basis of the numerical results, and it is shown that the Nusselt number is inversely proportional (1 + N) where N is the number of partitions.

91 citations

Journal ArticleDOI
TL;DR: In this article, an experimental and analytical study of the phenomenon of heat transfer by natural convection in a rectangular enclosure fitted with an incomplete internal partition is presented. But the authors do not consider the effect of the aperture ratio h/H on both the heat transfer rate and flow pattern.

88 citations