A numerical study of unsteady two-dimensional natural convection in stagnant fluid layers heated by solar radiation is carried out. The governing partial differential equations are solved numerically using the unconditionally stable alternating direction implicit method. Convection is found to set in as two counter-rotating eddies of unequal strength. Convection is seen to be encouraged by lowering the optical thickness of the fluid and increasing the albedo. The bottom boundary emissivity is important only at low and intermediate optical thicknesses where lowering boundary emissivity suppresses convection.
Energy Conversion and Management 12/1990; 30(2):91-100. DOI:10.1016/0196-8904(90)90018-T