Laminar natural convection is studied in a square cavity filled with air whose
two vertical sides are subject to a temperature difference, while the other two
horizontal sides are adiabatic. The hot and cold wall temperatures are kept
constant. We have presented a dynamic and thermal study of pure natural
convection for different values of the Rayleigh number. The numerical simu-
lation was carried out for Rayleigh numbers ranging from 102, 103, ..., 105 and
the Prandtl number is Pr = 0.71. We used the COMSOL Multiphysic 5.1
software, which allows us to simultaneously solve the coupled physical phe-
nomena in a square enclosure containing air under the Boussinesq approxi-
mation. For the coupling of natural convection with radiation from radiative
surfaces, both horizontal faces are subjected to radiative flux, and the emis-
sivity of the surfaces varies from Ԑ = 0.1 to 0.8. We have seen that a circula-
tion process is involved. The fluid that is subjected to a high temperature near
the hot wall rises to the ceiling and the fluid near the cold wall sinks. This
movement continues until the fluid reaches thermal equilibrium. In a natural
convection-surface radiation coupling, simulation results indicate that radia-
tive exchange decreases as a function of the Rayleigh number. Surface radia-
tion reduces the flow in the cavity.

Natural Convection Square Cavity