The natural convection from a protruding body in a cavity is a major intere
st in cooling and heating applications. In the present study, a natural con
vection due to a protruding body in a square cavity is investigated. The ef
fect of the aspect ratio of the protruding body on the resulting Nusselt nu
mber (Nu) is considered. The governing equations of flow and energy are sol
ved numerically. The intake and exit ports are allocated in the side walls
of the cavity and air is used as the environment within the cavity in the s
imulations. The entropy analyses due to heat transfer and fluid friction ar
e carried out for different aspect ratios. An empirical relation between Nu
and the aspect ratio is developed. It is found that the aspect ratio consi
derably influences Nu such that as the aspect ratio increases Nu reduces. T
he overall irreversibility to heat transfer ratio reduces with increasing a
spect ratio.