The results of numerical computations are presented for free convection under isothermal wall and constant-heat-flux wall-boundary conditions. The effects of the Prandtl, Grashof, and Rayleigh numbers, aspect ratio, and variable properties are described. Experimental measurements of net heat transfer through vertical plane layers and of velocity and temperature profiles are given for Prandtl numbers of 1 to 20,000. A comparison of the laminar data with the numerical results shows excellent correlation.

Nomenclature c p = specific heat at constant pressure, Btu/lbm-°F d = characteristic thickness, ft h = joint conductance, Btu/hr-ft 2 -°F k = thermal conductivity, Btu/hr-ft-°F L -characteristic length, ft q = energy dissipation per unit volume, Btu/hr-ft 3 q' = energy dissipation, Btu/hr R = scale model ratio S = energy flux per unit area, Btu/hr-ft 2 t = time, hr T = absolute temperature, °R [T] = parameter temperature dependance U = parameter uncertainty (tolerance) V = parameter value a = coefficient of thermal expansion a sj€ = solar absorptivity and emissivity, respectively p = density, lbm/ft 3 co = solid angle, steradians Subscripts m,p = scale model and prototype, respectively pe = probable error Superscript * = ratio of model/pro to type properties (i.e., k* = k m /k p )

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