On the effects of Rayleigh number and inlet turbulence intensity upon the buoyancy-induced mass flow rate in sloping and convergent channels

A numerical study on the mass flow rate induced by natural convection in a sloped converging channel for different inclination and convergence angles with symmetrical heating is reported. Two-dimensional, laminar, transitional and turbulent simulations were obtained by solving the fully-elliptic governing equations using two different general purpose codes: Fluent and Phoenics. In transitional and turbulent cases, the low-Reynolds image turbulence model was employed. Special emphasis was carried out, for turbulent regime, on the systematic comparisons of computational results with experimental and numerical data taken from literature, considering the influence of inlet turbulence intensity upon transitional point. Numerical results were obtained for wide and not yet covered ranges of the modified Rayleigh number varying from image to image, the aspect ratio between 0.03 and 0.25, the converging angle from 1° to 30° and sloping angle from 0° to 60°. A generalized correlation for the non-dimensional mass flow rate in a channel with isothermal plates and symmetric heating conditions is presented.