Abstract: “A numerical analysis was carried out to study the laminar natural convection in a three-dimensional enclosure. Main efforts were focused on the Rayleigh number (Ra), position of hot and cold sources on the flow structure and heat transfer characteristics are investigated in detail. Results reveal that by increasing in Ra from 103 to 106 the average Nusselt will be increase and the rate of heat transfer from hot and cold sources will be increase, also the maximum component of velocity will increase, The increase in the velocity component along the acceleration of gravity is higher than other component of velocity. According to the results by increasing the distance between heat sources rate of heat transfer between heat sources (average Nusselt) significantly decreased, also average temperature and maximum component of velocity in all direction will be increase.”

Keywords: Natural convection, enclosure, heat transfer, velocity component, flow structure