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

• Our results show that the Dufour number decreases the heat transfer coefficient.
• The Soret number is shown to decrease the mass transfer coefficient.
• In the presence of the buoyancy assisting force (Ri>0)(Ri>0), the velocity profile exhibits 35% velocity overshoot.
• The mixed convection parameter Ri and velocity ratio parameter tend to increase the magnitude of velocity overshoot.

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 ξξ (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 DfDf decreases the heat transfer coefficient while the Soret number SrSr decreases the mass transfer coefficient.