International Journal of Engineering and Technology

An analysis is performed to study the influence of temperature-dependent viscosity and thermal conductivity on the unsteady laminar free convection flow over a semi infinite vertical plate by taking into account the Dufour and Soret numbers. Both viscosity and thermal conductivity are variables and considered only a function of temperature. It is assumed that the viscosity of the fluid is an exponential function and thermal conductivity is a linear function of the temperature. The non-linear coupled dimensionless equations governing the boundary layer flow, heat and mass transfer are solved by using implicit finite-difference method of Crank-Nicolson type. An analysis of the effects of different parameters on dimensionless velocity, temperature and concentration profiles, as well as the local and average skin-friction and the rates of heat and mass transfer, is shown graphically.