Numerical Simulations of Natural Convection Inside Bi-Disperse Porous Medium Enclosure
B. V. K. Reddy1 and Arunn Narasimhan2
1Research Scholar, Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering,
Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
bvkreddy680@gmail.com
2Assistant Professor, Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering,
Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
arunn@iitm.ac.in
ABSTRACT
Bi-Disperse Porous Medium (BDPM) consists of a macro porous medium whose solid phase is replaced with a micro porous medium. Further, an enclosure filled with distributed solid blocks immersed in a convecting fluid can be treated as a porous medium enclosure. Combining these concepts, an enclosure filled with distributed blocks that are themselves microporous with macro-size gaps separating them, can be modelled as a BDPM enclosure. This study investigates using numerical simulations, steady natural convection inside a square BDPM enclosure made from uniformly spaced, disconnected square porous blocks that form the micro porous medium. The side walls are differentially heated, while the top and bottom ones are kept adiabatic. For a fixed macropore volume fraction (φE) and number of blocks (N2), the effect of internal Darcy number (DaI), internal micropore volume fraction (φI) and enclosure Rayleigh number (Ra) on the enclosure overall Nusselt number (Nu) is investigated. For fixed Ra, the Nu increases with increase in both DaI and φI. At low Ra values, the Nu is found to be strongly affected by DaI while φI exerts only a minor effect. At high Ra values, the porous blocks in the core region have negligible effect on the Nu.
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