Numerical simulation of mixed convection with film evaporation in a vertical channel

International audienceSimulations of laminar mixed convection in a vertical parallel-plate channel with vaporization of thin liquid films on wetted walls are presented to illustrate the effects of the thermal and solutal buoyancy forces on the flow field, heat and mass transfer. Results are specifically presented for air-water vapor and air-hexane mixtures considered as ideal gases under various boundary conditions and for large interfacial mass fractions. Steady laminar, two-dimensional flows are examined in detail and comparisons with usual problem formulations based on the Boussinesq approximation are presented. The elliptic flow model used allow to predict flow reversal as well as recirculation cells in the entrance region according to the differences in the molecular weights of the two mixture components. It is shown that rather large variations in the mixture density between the inlet and outlet sections may render the constant density assumption inappropriate, especially for the predictions of vaporized mass flux rate