In this paper, the effects of variable viscosity and thermal conductivity on coupled heat and
mass transfer by free convection about a permeable horizontal cylinder embedded in porous
media using Ergun mode are studied. The fluid viscosity and thermal conductivity and
are assumed to vary as a linear function of temperature while the mass diffusion is
assumed to vary as linear function of concentration. The surface of the horizontal cylinder
is maintained at a uniform wall temperature and a uniform wall concentration. The transformed
governing equations are obtained and solved by using the implicit finite difference
method. Numerical results for dimensionless temperature and concentration profiles as
well as Nusselt and Sherwood numbers are presented for various values of parameters
namely, Ergun number, transpiration parameter, Rayleigh and Lewis numbers and buoyancy
ratio parameter.