DOI: 10.1615/ICHMT.1997.IntSymLiqTwoPhaseFlowTranspPhenCHT
ISBN Print: 978-1-56700-115-0
ISSN: 2578-5486
THE PENETRATION OF UNSTEADY FREE CONVECTION FROM A HEATED AND COOLED VERTICAL FLAT SURFACE IN A POROUS MEDIUM
RESUMO
Unsteady two-dimensional free convection is generated by an impulsively heated and cooled, in space, infinite vertical flat surface which is embedded in a stationary porous medium. The matched asymptotic expansions technique is used to obtain approximate analytical solutions for small values of time and these results are found to be in very good agreement with the finite-difference results for all the values of the Rayleigh number considered, namely 0 ≤ Ra ≤ 100. It is found that the flow consists of a row of counter rotating cells, each cell developing along the hot or cold regions of the surface. For values of Ra larger than about 40, and for small times, two recirculating regions develop at the point of collision of the two opposite streams which flow along the surface. At large values of time the unsteady numerical solution converge to the steady state results.