The influence of free stream direction on mixed (natural and forced) convective heat transfer from a circular cylinder is investigated. The cylinder, which has an isothermal surface, is placed with its axis horizontal and normal to the oncoming flow. The free stream direction varies between the vertically upward (parallel flow) and the vertically downward (contraflow) directions. The investigation is based on the time integration of the unsteady, two-dimensional equations of motion and energy until reaching steady conditions. The study is limited to Reynolds numbers up to Re = 40 and Grashoff numbers of Gr = Re'. The results are compared with the available experimental data and the agreement is satisfactory.
Nusselt number distribution near a stagnation point for the two cases of Pr -+0 and Pr -+ co. The approach requires the existence of boundary-layer flow and is limited to the region surrounding the stagnation point, Sparrow and Lee8 obtained an approximate solution for the Nusselt number distribution in the neighbourhood of the forward stagnation point for the case of parallel flow past a circular cylinder. The solution is based on the boundary-layer flow assumption and the problem