Effects of variable chemical reaction and variable electric conductivity on free convective heat and mass transfer flow along an inclined stretching sheet with variable heat and mass fluxes under the influence of Dufour and Soret effects

M U U Ahammad,M S S Alam

doi:10.15388/na.16.1.14110

Abstract

This paper deals with the effects of variable chemical reaction and variable electric conductivity on free convection and mass transfer flow of a viscous, incompressible and electrically conducting fluid over an inclined stretching sheet with variable heat and mass fluxes under the influence of Dufour and Soret effects. The non-linear boundary layer equations with boundary conditions are transferred into a system of non-linear ordinary differential equations using an established similarity transformation. These non-linear and locally-similar ordinary differential equations are solved numerically by applying Nachtsheim–Swigert shooting iteration technique with sixth-order Runge–Kutta integration scheme. Comparison with previously published work is obtained and excellent agreement is found. The effects of various parameters on the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, heat and mass transfer rate from the stretching sheet to the surrounding fluid are presented graphically and in tabulated form for a hydrogen-air mixture. The numerical results showed that chemical reaction parameter K, order of reaction n, Dufour number Df , Soret number Sr and heat (or mass) flux parameter r play a crucial role in the solutions.

Highlights

Coupled heat and mass transfer problems in presence of chemical reaction are of importance in many processes and have received considerable amount of attention in recent times
In this paper we have studied numerically the effects of variable chemical reaction and variable electric conductivity on free convection and mass transfer flow of a viscous, incompressible and electrically conducting fluid over an inclined stretching sheet with variable heat and mass fluxes under the influence of Dufour and Soret effects
From the present numerical investigations we see that the velocity profiles decrease with the increasing values of magnetic field parameter, suction parameter, angle of inclination to the vertical, heat flux parameter and chemical reaction parameter whereas it increases with increasing value of order of chemical reaction

Summary

Introduction

Coupled heat and mass transfer problems in presence of chemical reaction are of importance in many processes and have received considerable amount of attention in recent times. Alam et al [7] investigated the effects of variable chemical reaction (where n was taken 1, 2 and 3), thermophoresis, temperature dependent viscosity and thermal radiation on an unsteady MHD free convective heat and mass transfer flow past in impulsively started infinite inclined porous plate. Afify [16] obtained similarity solution for the effects of thermal diffusion and diffusion thermo on MHD free convective heat and mass transfer over a stretching surface considering suction or injection His numerical results indicate that for fluids with medium molecular weight (H2, air), Dufour and Soret effects should not be neglected and the suction as well as injection parameter has significant impact www.lana.lt/journal in controlling the rate of heat transfer in the boundary layer.

Governing equations of the flow and similarity analysis

Numerical solution

Results and discussion

Conclusions