Simultaneous natural-convection heat transfer above and below an isothermal horizontal thin plate

Numerical studies were conducted to investigate the simultaneous natural-convection heat transfer above and below an isothermal thin plate in an infinite space. The full two-dimensional conservation equations for laminar flows were solved. The numerical approach was based on the finite-volume technique with a nonstaggered grid arrangement. The SIMPLE algorithm was used for handling the pressure-velocity coupling. Plate width and temperature were used to vary the Rayleigh number over the range 1.0 × 10⁵ to 1.7 × 10⁷. The expressions for numerical local and average Nusselt number were correlated, and horizontal velocity and temperature profiles were provided. It was found that the upper-surface Nusselt numbers are smaller than the corresponding lower-surface Nusselt numbers. Numerical results for upward- and downward-facing isothermal horizontal plates (single-sided heat transfer) were also shown for comparison. For these cases, Nusselt numbers on the upward-facing surface are larger than those on the downward-facing surface.