NUMERICAL EXAMINATION OF NATURAL CONVECTION AND ENTROPY FORMATION INSIDE AIR-SATURATED POROUS ENCLOSURE TO CREATE THERMALLY ACTIVE REGION WITH PERIODIC HEATING/COOLING

The creation of a thermally active zone in a porous channel could find relevance in a number of application areas of industrial and scientific relevance. In line with this need, the current study focuses on the numerical prediction of buoyancy-driven thermal and fluid flow behavior inside a porous channel with periodic temperature profile, subjected to the bottom wall. Temperature distribution inside the cavity can be precisely controlled within a specified temperature band by creating periodical perturbation from the bottom wall. The key parameters for this work are Darcy number (Da, changed from 10(-4) to 10(-1)), Rayleigh number (Ra, changed from 10(3) to 10(6)), and wavelength of periodic heating/cooling (lambda/H, varied from 4 to 0.25). Circulation patterns, entropy formation, and heat transfer rate are found to vary significantly with Ra, Da, and lambda/H. One noteworthy surveillance, found in this study, is the formation of global circulation, instead of small circulations inside the cavity with lower periods of heating (lambda/H < 1) in the regime of high Ra and Da.