Abstract
This paper represents a numerical investigation of the effect of temperature dependent thermal conductivity on unsteady
naturalconvection flow past a semi-infinite isothermal vertical cylinder immersed in air. The thermal conductivity is adopted to
vary thetemperature. The governing non-dimensional boundary layer equations have been solved numerically employing an
explicit finitedifference method. To interpret the influence of variable thermal conductivity on the velocity and temperature
profiles aparametric study is accomplished. The numerical consequences disclose that the thermal conductivity has significant
influence ontransient velocity and temperature profiles, average skin friction coefficient and average heat transfer rate. The
conclusionindicates that when the thermal conductivity parameter increases the temperature and skin friction coefficient increases
but thevelocity near the wall and Nusselt number decreases. We have also shown the effect of thermal conductivity variation
parameteron isotherms and streamlines