Turbulant natural convection inside a parallelepiped with heating of two opposite vertical walls

The results of numerical study of three-dimensional turbulent natural convection in the air inside a parallelepiped with uniform heating of two opposite vertical side walls are presented. The cross section of the enclosure was constant (a square), and the elongation degree was varied over wide range $A_x = L/H = 0.1$–$5$. The Rayleigh number was changed within the range $\text{Ra} = 10^9$–$10^{11}$. The effect of the geometry of the enclosure on the structure of the three-dimensional flow and heat transfer have been studied for short and long cavities. It is shown that for the extended enclosures $(A_x > 1.0)$ the average heat transfer can be calculated using two-dimensional models.