NUMERICAL SIMULATION OF TURBULENT NATURAL CONVECTION AND HEAT TRANSFER IN A RECTANGULAR ENCLOSURE USING THE 𝒌 − 𝝎 MODEL

ABSTRACT

Turbulent flow is a type of fluid flow in which the fluid undergoes irregular fluctuations. The velocity of the fluid at a point is continuously undergoing changes in both magnitude and direction. Turbulent natural convection has been studied both numerically and theoretically. It plays an important role in the field of heat transfer and buildings environment. A numerical study was performed on a rectangular enclosure with varying Rayleigh numbers to determine velocity, temperature distributions and turbulent intensities of a two dimensional buoyancy driven turbulent flow. The vertical walls of the enclosure are kept at a constant temperature difference of 18𝐾 while horizontal walls are adiabatic. The RANS, energy and turbulent transport equations with Boussinesq approximations were discretized using Finite Difference method. The low Reynolds 𝑘 −omega (𝑘 − 𝜔) two equation model was used. The Rayleigh number range 1010 ≤ 𝑅𝑎 ≤ 1013 with constant Aspect ratio and Prandtl number 0.71 were used. The contours of total temperature distribution, velocity magnitude and turbulent intensity have been represented. Based on the numerical results as the Rayleigh number increases, the turbulent intensity increases.