Effects of Radial Fins on the Laminar Natural Convection of a Nanofluid in Concentric Annuli

Abstract

The laminar natural convection of the Cu-water nanofluid between two horizontal concentric cylinders with four radial fins attached to the inner cylinder is studied numerically. The governing equations with the respective boundary conditions are solved by using the finite volume method and the SIMPLER algorithm. The computations are performed for various Rayleigh numbers, fin lengths, and thermal conductivity ratios. The results presented in this study are for a range of Rayleigh numbers from 103 to 105, dimensionless lengths of the fins between 0.1 to 0.4, and two thermal conductivity ratios, namely, 100 and 654. It is observed from the results that the average Nusselt number decreases with increasing the fins' lengths. However, the heat transfer rate and the average Nusselt number increase by increasing the fins' thermal conductivity at high Rayleigh numbers.