Two dimensional numerical simulations are conducted to investigate the heat transfer in a square cavity where a heat source of a constant and uniform temperature is located on the middle of a vertical side wall, the other side wall is kept isothermal at the temperature lower than that of the heat source, the rest of the wall is adiabatic and an adiabatic object is located inside. It has been found that the heat transfer is enhanced at certain values of the height of the object. It has been also found that in the cases where the flow pattern between the heater and the object resembles the one in the channel between parallel plates, the heat transfer characteristics are well correlated by using modified Nusselt and Grashof numbers.