Numerical Analysis of Natural Convection Heat Transfer and Fluid Flow in Concentric and Eccentric Annulus

Concentric and eccentric annulus is used frequently in technical and industrial applications such as nuclear reactors, thermal storage system and etc. In this paper, computational fluid dynamics (CFD) is used to investigate two dimensional free convection of laminar flow in annulus with isotherm cylinders surface and cooler inner surface. Problem studied in ten different cases. Due to natural convection continuity and momentum equations are coupled and must be solved simultaneously. Finite volume method is used for discreting and solving governing equations. The purpose was to obtain the eccentricity effect on Nusselt number so streamlines and temperature fields must be determined. Results shown that the highest Nusselt number values occurs in  0.5 e l upward eccentricity for inner cylinder and  0.3 e l upward eccentricity for outer cylinder and e l is degree of eccentricity. Side eccentricity reduces the outer cylinder Nusselt number but increases inner cylinder Nusselt number. Correlations are included to calculate the Nusselt number of the cylinders.