Ans:
- The region beyond the entrance region in which the velocity profile is fully developed and remains unchanged is called the hydrodynamically fully developed region.
- As shown in the figure above, in the hydrodynamic entrance region the flow is not yet fully developed and it has not yet attained the parabolic velocity profile.
- In the fully developed region the velocity profile becomes parabolic and it remains constant.
- The shear stress is the function of the slope of the velocity profile at the surface, hence it remains constant too in fully developed flow.