Free heat and mass convection in a trapezoidal enclosure.

A study of the natural heat and mass transfer in a trapezoidal cavity heated from the bottom and cooled from the inclined upper wall is undertaken in this article. Momentum, energy and concentration equations are computed by finite volumes method. The obtained results show that the flow configurations depends on the a angle inclination of the upper wall. We observe first for weak angles, that the flow configuration is a type of Rayleigh-Benard cells, and second, for the large angles, that the flow configuration is a type of differentially heated rectangular enclosure. The influence on heat and mass transfer rate as a function of thermo-solutals solicitations is studied. The influence of geometry and the nature of the species is also examined. The heat and mass transfer rates increase accordingly as the aspect ration Al increases. The decrease of the Lewis number Le causes an increase in the heat and mass transfer rates. The solutal solicitation is of the same nature as the thermal solicitation. The two solicitations are cooperant and an increase of one them will increase the two transfer rates. (C) Elsevier, Paris.