Numerical Study of Natural Convection In Annular Enclosure with Linearly Varying Wall Temperature

Natural convection heat transfer with two-dimensional in an annular enclo¬sure is examined numerically for Rayleigh numbers rating from 103 to 105and for aspect ratios 1,2,3. The outer wall is heated using a linear temperature while the inner wall of the annular enclosure was cold, the top and bottom ends was adiabatic.The stream function– formulation was used in the mathematical model of the case under discussion where the differential equations were converted to algebraic equations using finite differences method. The numerical solution ability to calculate stream function, temperature and Nusselt number during the computational domain. The numerical results showed that the main process of heat transfer is conduction for Rayleigh number less than Ra≤103, and convection for Rayleigh number greater than Ra>103. Average Nusselt number is increased with aspect ratio increasing for Ra ranging with (103-105) because increasing of heat transfer area. To ensure the reliability of the numerical solution a comparison of the current results with that of previous research, shows a good agreement between the results and this is confirms the validity and reliability of the current model.Key words: natural convection, annular, enclosure, numerical, laminar.