LAUSR

Abstract A study of shape effect on natural convection heat transfer from a vertical solid frustum either suspended in air or placed on ground has been numerically simulated in laminar range of Ra spanning from 104 to 108 while keeping the surface area same for all different frustums. The heat loss from the frustums has been compared with the corresponding cylinders having same surface area as that of the frustums. It has been observed that the heat loss from both the frustums, straight or inverted, is always less than that of the cylinders for all Ra. When both the frustums are placed on the ground the straight frustum always loses more heat than that of the inverted one. A considerable difference in the average Nu between straight and inverted frustum (on ground) was observed at all Ra and θ. The average Nu of both straight and the inverted frustum on ground, varies with the inclination, θ, of the lateral surface. However, when both of them are suspended in air, the inverted frustum loses more heat than the straight one for Ra