TRANSIENT NATURAL CONVECTION OF WATER NEAR ITS DENSITY EXTREMUM IN A RECTANGULAR CAVITY FILLED WITH POROUS MEDIUM

A numerical study is performed to analyze the transient flow field and heat transfer behavior of cold water in a rectangular enclosure filed with a porous medium. The numerical method was employed by the SIMPLE-C algorithm. The accurate nonlinear relation between density and temperature developed by Gebhart and Mollendorf was used. The numerical results show that, for R l, only one counterclockwise vortex exists in the space the entire time. For τ > 10 −3 , the heat transfer rate increases with increase in Darcy number for the entire time. However, as time increases, the heat transfer rate on the high-temperature surface decreases and that on the low-temperature surface increases.