Correlation for Nusselt number in natural convection in vertical convergent channels at uniform wall temperature by a numerical investigation

A numerical study of natural convective flows in a vertical converging channel for different angles of convergence has been carried out, taking into account the lacks reported in the literature on some aspects of this configuration. Two-dimensional laminar simulations were obtained by solving the fully elliptic governing equations using two different general purpose codes: Fluent and Phoenics. Special emphasis is made on the systematic comparisons of computational results with experimental and numerical data taken from literature. A generalized correlation for the average Nusselt number has been obtained from numerical results in a channel with isothermal heated plates, for symmetric and asymmetric heating conditions. This correlation has been obtained for wide and not yet covered ranges of the modified Rayleigh number varying from 1 to 106 and the angle of convergence from 1° to 30°. Good agreement has been obtained with respect to the available experimental asymptotes of the bibliography for fully developed and boundary layer regimes.