Thermal diffusion and diffusion-thermo effects on mixed convection from an exponentially impermeable stretching surface

The objective of the present article is to investigate the Dufour (diffusion-thermo) and Soret (thermal diffusion) effects on the steady double diffusive mixed convection boundary layer flows over an impermeable exponentially stretching sheet in an exponentially moving free stream under the influence of chemically reactive species. The nonlinear partial differential equations governing the flow, temperature and species concentration fields are expressed in non-dimensional form with the help of suitable non similar transformations. The resulting final non-dimensional set of coupled nonlinear partial differential equations is solved by using an implicit finite difference scheme in conjunction with the Newton's linearization technique. The effects of various governing parameters involved in the velocity, temperature and species concentration fields are discussed in this article. The results display that the streamwise co-ordinate xi (non-similarity variable) profoundly influences the flow, thermal and concentration fields which reveal the accountability of non-similar solutions. Results also indicate that the Dufour number D-integral decreases the heat transfer coefficient while the Soret number S-r decreases the mass transfer coefficient. (C) 2016 Elsevier Ltd. All rights reserved.