Numerical analysis of radiative effects on natural convection in vertical convergent and symmetrically heated channels

Natural convection in a convergent channel with finite-thickness principal walls at uniform heat flux is investigated numerically. Heat conduction in the walls and the effects of walls emissivity are taken into account. Laminar two-dimensional steady-state conditions are assumed. Results in terms of wall dimensionless temperature profiles as a function of convergence angle, channel spacing, and heat flux are given for various values of wall emissivity. Wall temperatures decrease significantly, passing from delta = 0 degrees to 2 degrees at the lowest channel spacing. Streamlines and temperature fields show a recirculating region in the channel for large values of L-w/b(min) and for delta equal to 5 degrees and 10 degrees. Correlations between Nusselt numbers and Rayleigh numbers are proposed. Dimensionless parameters are in the following ranges: 4.4 <= Ra'(bmin) 0 <= 1.5 x 10(5), 10 < L-w/b(min) <= 58, 0.0 <= epsilon <= 1.0, and 0 degrees <= delta <= 10 degrees. Numerical predictions are in very good agreement with experimental data.