FREE CONVECTIVE FLOW IN AN ENCLOSURE WITH A COOLED INCLINED UPPER SURFACE

Natural convective air flow in an enclosure with a horizontal lower wa ll, vertical side-walls and a straight inclined top wall has been nume rically studied. The lower wall is at a uniform high temperature while the top wall is cooled to a uniform lower temperature. The temperatur e of the side-walls varies in a prescribed way between the temperature s of the bottom and top walls. This flow situation is related to that occurring in a proposed system for use in ''developing'' countries for drying crops such as corn and rice. It has been assumed that the flow is steady, laminar, and two-dimensional and that the fluid properties are constant except for the density change with temperature that give s rise to the buoyancy forces. The governing equations have been expre ssed in terms of stream function and vorticity and written in dimensio nless form. The finite element method has been used to obtain the solu tion to these dimensionless equations. Results have been obtained for enclosures with aspect ratios of between 0.25 and 1 for top surface an gles of inclination of between 0 and 45-degrees and for Rayleigh numbe rs, based on the enclosure width, of between 1000 and 10(7). The resul ts have been used to study the effect of changes in the governing para meters on the flow pattern in the enclosure and on the mean heat trans fer rate to the upper surface.