Developed heat transfer
Convective heat transfer in a pipe at such a distance from the entrance beyond which the prescribed boundary conditions at the wall govern the exchange processes so that the temperature field is essentially independent of the nature of the temperature and velocity distribution at the entrance.
Comment. When the properties of the fluid remain constant for certain types of boundary conditions at the wall (e.g., constant wall temperature or constant heat flux at the wall), the temperature distribution (measured from the wall temperature) over the flow section in the case of developed heat transfer remains self-similar at different cross sections of the pipe. Moreover, the heat transfer coefficient, referred to the local temperature difference, does not change over the length of the pipe.