Laminar natural convection flow around horizontal heated cylinder with and without confinement is numerically studied. Confinement is done above or below the cylinder at various vertical positions. Two-dimensional computational models using finite volume formulation have been developed and validated against experimental data. Local heat transfer predictions are correlated for an unconfined single cylinder. The significance of confinement on the top and bottom side of the cylinder is clearly demonstrated for a wide range of Ra, and spacing between the cylinder and the confinement. In case of top confinement, the increase in Nu(theta) at the upper portion of the cylinder depends on the position of the wall. The confinement below the cylinder caused a reduction in (Nu) over bar at the bottom half of the cylinder as compared to the top half. For both cases, the effect of confinement can be neglected at high HID ratios. (C) 2014 Elsevier Ltd. All rights reserved.