Thermal-diffusion and diffusion-thermo effects on magnetohydrodynamics heat and mass transfer

Abstract

The thermal-dIffusion and diffusion-thermo effects on Magnetohydrodynamics (MAD) heat and mass transfer boundary layer flow have been studied numerically. The governing equations are then made dImensionless by I.lsing I.lsual similarity transformations. The dimensionless equations are solved numcneally by applying Nachtsheim-Swlgert shooting iteration techmque along with Rungc-Kmta sixth order integration method. A two-dimensional steady MHD combined free-forced convedion and mass transfer flow past a semi-infmlte vertical plate is investigated. The effects of magnelle parameter M, thermal-diffusion parameter Sr (Soret numher) and diffusion-thermo parameter Df (Dufol.lr numher) have been examined on the 110wfield of a hydrogen-air mixture as. a non-chemical reactmg fluid pair. The analysis has shown that the 110w field is appreciably influenced by the thermal-dIffusion and diffusion-thermo effects. In our study we have also found that the present results are in excellent agreement with Kafoussia~ (1990), when M == Df == Sr = O. Next, the above effects have been analyzed on unsteady MHD free convection and mass flow pa~t an mfinite vertical porous plate. Two eases are considered (I) Impulsively started plate (ISP) and (ii) Uniformly accelerated plate (UAP). Similarity equal10ns of the momentum, energy and concentration equations are derived by mtroducing a time dependent length scale. The dimensionless velocity, temperature and concentration profiles are shown graphically for different values of the parameters entenng into the problem. The numerical valLlCsof the local skm-friction, local Kusselt number and local Shelwood number are aho presented in tabular form.