Abstract
Natural convection in a steady state of incompressible air inside a cavity’s porous with a heated low wall of a sinusoidal profile is investigated numerically in this paper. The upper horizontal wall is kept cold while the two sides are thermally insulated. The proposed physical model was developed and studied with two-dimensional conditions, using the finite element method and adapting the Darcy-Brinkman model. This paper examines the laminar natural convection in a square porous cavity for different Rayleigh numbers (10 ≤ Ra ≤ 104), aspect ratios (0.25 ≤ AR ≤ 1.0), and sinusoidal temperature amplitude (0.25 ≤ λ ≤ 1.0). Moreover, the variation effect of Ra, AR, and λ on isotherms, streamlines, and the mean and local Nusselt numbers has been presented and analyzed. The results showed that an increase in the sinusoidal thermal amplitude, mean Nusselt number, and AR reduced somewhat the Rayleigh number. This provided a solution in which the mean Nusselt number increased by increasing the sinusoidal thermal amplitude and the Rayleigh number. On the other hand, it decreases slightly by increasing the AR. In addition, the convection transfer mechanism is the main mode when the Rayleigh number is high. Thus, it was found that the Darcy number also has an effect on heat transmission. The obtained results were compared with those found in the literature and were found to be in good accordance.
Highlights
It is observed that the heat exchange can be improved by using porous media
In order to improve the performance of heat transfer within the porous medium, we have studied a new function totally absent in the literature, and yet widely encountered in natural and industrial processes, where thermal heating takes the form of the cosine function, i.e. the heating is concentrated in the middle and distributed to the periphery
The main objective of this paper was to study the impact of the sinusoidal temperature on the heat flow and the current lines in a porous cavity subjected to natural convection while varying the Rayleigh number, the amplitude sinusoidal temperature, and the cavity format ratio parameter
Summary
It is observed that the heat exchange can be improved by using porous media. The term "porous medium" is generally referred to the solid complex shape which contains cavities or interstitial voids accessible to a fluid. In a porous medium multiple physicochemical and transport phenomena take place. It was often considered as a homogeneous and isotropic medium, it was considered anisotropic in its mechanical and thermal properties in various practical applications. The interstitial fluid flow in a porous medium is caused by convective heat transfer. This type of convection can be caused by different natural forces like the gravity force and the variation in density caused by the temperature difference. Lowtemperature gradients affect the mass and heat transport that occurs in a porous medium. This type of convection is important in a wide range of industrial and natural
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