Numerical study of natural convection in an annulus

Abstract

In this paper, 2-D laminar free convection thermal transmission has been investigated numerically. Double concentric rectangular enclosures with discrete heaters were studied using COMSOL Multiphysics 6.0 software package. Heat flux was applied using specific number of heaters as well as changing the number and distances of the heaters in each case. Heaters were installed on the left vertical wall of the enclosure the opposite wall was kept at constant temperature. The horizontal walls were considered adiabatic. Air was taken as working fluid and all the features of air were considered constant except the change in density due to buoyancy forces that are driving the fluid. Finite volumes method was chosen for solving the governing equations in the dimensionless formula. The effect of Rayleigh number on Nusselt number was analyzed using the resultant isothermal contours. We attained the results for different values of Rayleigh number. A large enhancement in thermal transmission was achieved in the attained results, it was found that the amount of thermal energy transmitted will increase by increasing the value of Ra.