Oscillatory Chemically-reacting Mhd Free Convection Heat and Mass Transfer in a Porous Medium with Soret and Dufour Effects: Finite Element Modeling

The effects of thermo-diffusion (Soret effect) and diffuso-thermal gradients (Dufour effect) on the unsteady incompressible magneto-hydrodynamic (MHD) free convection flow with mass transfer past a semi-infinite vertical plate in a Darcian porous medium in the presence of significant thermal radiation, first order homogenous chemical reaction and viscous heating are analyzed. The governing differential equations are non-dimensionalized using a similarity transformation rendering a system of coupled, nonlinear partial differential equations which are solved numerically using the robust, extensively-validated finite element method. Dimensionless velocity (U) is decreased with increasing magnetic parameter (M). An increase in Eckert number (Ec) causes greater mechanical energy to be dissipated as thermal energy and enhances fluid temperatures (θ). An increase in chemical reaction parameter (γ) increases velocity (U), temperature (θ) and also concentration value (φ). Temperatures (θ) are elevated substantially with decreasing Soret number (Sr) and simultaneous increasing Dufour number (Du). Concentration values (φ) are conversely enhanced with increasing Soret number (Sr) and a concurrent decrease in Dufour number (Du). Both temperature and velocity are suppressed with a rise in heat absorption parameter ( Φ ); On the other hand an increase in thermal radiation absorption parameter (Q1) generates an increase in both velocity and temperature fields. Increasing Schmidt number (Sc) is found to cause a decrease in both temperature and concentration profiles. Finally, the numerical values of local skin friction, local rate of heat transfer parameter and local mass transfer parameter are also presented in tabular form. The present problem has significant applications in chemical engineering materials processing, solar porous wafer absorber systems and metallurgy.