EFFECTS OF SIDEWALL HEAT LOSS ON CONVECTION IN A SATURATED POROUS VERTICAL SLAB.

First, a linear stability analysis is carried out for a system with impermeable boundaries. The sidewall temperature increases linearly with depth while the smaller-area endwalls are insulated. Convection occurs when the Rayleigh number R is asymptotically large relative to the inverse square of the horizontal aspect ratio. The convection pattern is composed of an integer number of vertically oriented three-dimensional, finger-like cells. This somewhat surprising type of modal configuration is also found when there is a specified vertical mass flux through the slab. It is concluded that sidewall heat loss has a very strong stabilizing effect on the initiation of buoyancy-induced convection relative to the more traditional situation where side- and endwalls are insulated. Furthermore the appearance of slender, finger-like convection cells is characteristic of motion in a narrow vertical-slab configuration. Finally it is noted that the precise modal configuration selected by a system is extremely sensitive to the value of the Rayleigh number.