Numerical Study of Natural Convection Between Two EccentricCylinders by Computational Fluid Dynamic Method

Natural convection between two eccentric cylinders has many applications in engineering problems. In this study, the laminar natural convection between two eccentric horizontal cylinders with infinite lengths, at moderate Rayliegh Numbers (103-106) was investigated by CFD technique. The cylinders are assumed to be isotherm, such that the surface temperature of inner cylinder is greater that the outer one. In this analysis, the simultaneous numerical solution of the continuity, momentum and energy equations are obtained in twodimensional condition using the Boussinesq approximation and employing the appropriate buoyancy term in the momentum equation. Considering the complexity of the physical geometry, conformal mapping is used to generate an orthogonal grid and the governing equations are transformed to a simple rectangular computational domain. Discretized forms of transformed equations are obtained by the control volume method and solved by the SIMPLE algorithm. By this method, the fluid velocity, pressure and temperature distributions are calculated and the effects of many parameters such as the clearance ratio, eccentricity and the Rayliegh number on thermohydrodynamic characteristics and particularly on convection coefficients are examined.

Keywords:

Natural convection , Eccentric cylinders