effect of viscous dissipation on seady natural convection heat and mass transfer in a vertical channel with variable viscosity and thermal conductivity

In this study, effects of viscous dissipation and variable physical properties on steady natural convection heat and mass transfer flow through a vertical channel were investigated. the variability in viscosity and thermal conductivity are considered linear function of temperature. the governing equations are transformed into a set of coupled nonlinear ordinary differential equations and solved using differential transformation method (dtm). results obtained were compared with exact solution when some of the flow conditions were relaxed and results from dtm show an excellent agreement with the exact solution which was obtained analytically. the influence of the flow parameters on fluid temperature, concentration and velocity are presented graphically and discussed for variations of the governing parameters. from the course of investigation, it was found that increasing viscous dissipation causes fluid temperature, velocity as well as the skin friction on the surface of both channels to increase. however, increasing the fluid viscosity retards the fluid motion and causes fluid temperature to decrease.