Numerical Study of Natural Convection Heat Transfer in an Inclined Porous Cavity with Time-Periodic Boundary Conditions

Abstract

Kalabin et al. (Numer. Heat Transfer A 47, 621-631, 2005) studied the unsteady natural convection for the sinusoidal oscillating wall temperature on one side wall and constant average temperature on the opposing side wall. The present article is on the unsteady natural convective heat transfer in an inclined porous cavity with similar temperature boundary conditions as those of Kalabin et al. The inclined angle ϕ of the cavity is varied from 0 • to 80 • . The flow field is modeled with the Brinkman-extended Darcy model. The combined effects of inclination angle of the enclosure and oscillation frequency of wall temperature are studied for Ra * = 10 3 , Da = 10 −3 , ε = 0.6, and Pr=1. Some results are also obtained with the Darcy-Brinkman-Forchheimer model and Darcy's law and are compared with the present Brinkman-extended Darcy model. The maximal heat transfer rate is attained at the oscillating frequency f = 46.7π and the inclined angle ϕ = 42.2 • .

Three-dimensional numerical study of natural convection in an inclined porous cavity with time sinusoidal oscillating boundary conditions

“…This suggests that, the heat flux is positive from the oscillating temperature wall (X = 0) to the constant temperature wall (X = 1) in spite of the net zero temperature difference between these two walls in a time-averaged sense. These findings agree with the two-dimensional results for both the clear (Kalabin et al, 2005) and porous flows (Wang et al, 2008a). Furthermore, it is found that, when the porous cavity is seriously inclined (a 1 = 80°, 86°and 90°, see Fig.…”

“…Furthermore, it is obvious that, all these roll-cells are parallel to each other and their rotating axes are perpendicular to x-z-surface. These findings indicate that, when the porous cavity is moderately inclined, the flow patterns inside are quasi two-dimensional and the transition phenomena are similar to those of Wang et al (2008a). However, if the porous cavity is more seriously inclined (a 1 P 80 ; a 2 ¼ 0 ), the flow patterns inside would be more complex and the transport phenomena should be quite different.…”

“…Furthermore, in all previous studies, the inclined cavity was only rotated around single axis (parallel to the hot and cold surfaces), and the effects of other inclination angles are still unknown, which would also be interesting and important for applications. With these motivations, in the present study, we further study the natural convections in an inclined porous cavity with three-dimensional method, where the boundary conditions are similar to those of Wang et al (2008a). Our objective is to investigate the three-dimensional natural convection characteristics with the combination effects of inclination angles and temperature oscillation frequency, especially when the porous cavity is seriously inclined, and find out the maximal heat fluxes at optimal combinations of these effects.…”

Effect of Time Periodic Boundary Conditions on Convective Flows in a Porous Square Enclosure with Non-Uniform Internal Heating

“…It is shown that the convection intensity within the enclosure increases linearly with heating amplitude while the resonance frequency was shown to be independent of the heating amplitude for both clear fluid and porous medium configurations. Recently, Nithyadevi et al (2006), Wang et al (2007, 2008a,b) and El Ayachi et al (2008 studied time-oscillating boundary condition on natural convection in porous enclosure. All these studies indicate that heat transfer in a system can be significantly augmented.…”

Buoyancy-driven convection heat transfer of copper–water nanofluid in a square enclosure under the different periodic oscillating boundary temperature waves

“…influencing factors of unsteady natural convection are more complex than those of steady natural convection [9][10][11][12], and studies are very scarce on natural convection in the nanofluids-filled enclosure with time-dependent boundary conditions [13], that is why further research is needed.…”