Effect of radial fins on two-dimensional turbulent natural convection in a horizontal annulus

Turbulent natural convection between two horizontal concentric cylinders in presence of radial fins is studied numerically. Turbulence modeling was done using a standard k-epsilon model. The conservation equations of mass, momentum and energy along with modeled equations of turbulent kinetic energy and its dissipation rate were discretized using control-volume approach. Results are obtained in the form of streamline and temperature contours for a number of radial fins ranges from 2 to 12 which are attached to the inner cylinder. Two different configurations are investigated for the case of two and four radial fins to reveal the effect of fin height and fin configuration. The Rayleigh number considered in this study ranges from 10(6) to 10(9). Results obtained for local Nusselt number variation of the inner cylinder shows that fin arrangement has no significant effect on heat transfer and higher fin heights have a blocking effect on flow causing lower heat transfer rate. It is observed that there is a reduction of heat transfer rate in all of the configurations considered in this study as compared to the case of no fin at the same Rayleigh number. There is also an increase in Nusselt number prediction with increasing Rayleigh number, which is a general behavior for all of natural convection problems. (C) 2003 Elsevier SAS. All rights reserved.