Soret and Dufour Effects on Natural Convection Heat and Mass Transfer Flow past a Horizontal Surface in a Porous Medium with Variable Viscosity

摘要

The heat and mass transfer characteristics of natural convection about a horizontal surface embedded in a saturated porous medium subject to variable viscosity are numerically analyzed, by taking into account the diffusion-thermo (Dufour) and thermal-diffusion (Soret) effects. The governing equations of continuity, momentum, energy and concentration are transformed into non-linear ordinary differential equations, using similarity transformations and then solved by using Runge-Kutta-Gill method along with shooting technique. The governing parameters of the problem are variable viscosity (θ_c), buoyancy ratio (N), Lewis number (Le), Prandtl number (Pr), Dufour number, Soret number and Schmidt number. The velocity, temperature and concentration distributions are presented graphically. The Nusselt number and Sherwood number are also derived and discussed numerically.