A numerical investigation of an unsteady mixed convection from a horizontal circular cylinder is presented. The coupled basic equations of motion and energy are sohed for two cases: 1) Re = 100. Gr= 104 and 2) Re = 200, Gr= 5xl04. The velocity field and the temperature field around the cylinder are cxliibited by streamlines and isotherms at different times. The Strouhal number for the shedding of vortices in the wake of the cylinder is calculated. Figures have been drawn to show the variations of the local and the mean Nusselt numbers with time. The effects of the presence of free convection are discussed.
