Theoretical investigation of an unsteady MHD free convection heat and mass transfer flow of a non-Newtonian fluid flow past a permeable moving vertical plate in the presence of thermal diffusion and heat sink

摘要

The problem of unsteady, two-dimensional, laminar, boundary-layer flow of a viscous, incompressible, electrically conducting and heat-absorbing Rivlin-Ericksen flow fluid along a semi-infinite vertical permeable moving plate has been investigated. A uniform transverse magnetic field is applied in the direction of the flow. The presence of thermal and concentration buoyancy effects is considered. The plate is assumed to move with a constant velocity in the direction of fluid flow while the free stream velocity is assumed to follow the exponentially increasing small perturbation law. Time-dependent wall suction is assumed to occur at the permeable surface. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. Numerical evaluation of the analytical results is performed and some graphical results for the velocity, temperature and concentration distributions within the boundary layer are presented. Skin-friction coefficient, Nusselt number and Sherwood number are also discussed with the help of the graphs. Local skin-friction coefficient increases with an increase in the permeability parameter, and Soret number whereas reverse effects is seen in the case of dimensionless viscoelasticity parameter of the Rivlin-Ericksen fluid. Nusselt number decreases in the presence of heat absorption. The presence of Soret number Sherwood number increases.