Due to flow non- uniformities in transition region, the thermal entrance region
length can only be determined experimentally by measuring the temperature distribution along the thermal boundary layer.
Fig 3 and 4 shows plot of local convective heat transfer coefficient along dimensionless axial distance from the tube entrance region
Taneda  stated that transition in pipe flow occurs only in the entrance region
The stratification phenomenon significantly exacerbates this heat transfer in the entrance region
of horizontal pipes.
It can be inferred that for the teeth development it should be initiated in the entrance region
These results have shown the good agreement with the conventional theories even for the entrance region
of the tube.
1999) studied solids holdup and particle velocity at the entrance region
with three types of gas-solid distributor designs, but the study was in a downer, not a riser.
Two-dimensional laminar flow and heat transfer in the entrance region
of a symmetric wavy-channel with constant wall heat flux density which includes fourteen undulations are presented.
1] developed the correlation for heat source elements situated in electronic equipment cooling which is the ratio of convective heat transfer co-efficient at entrance and fully developed region which is independent of Reynolds number but dependent only on no of rows situated near by entrance region
2006), the pressure gradient in the entrance region
of a pipe where the flow is developing is different from that which occurs downstream in a fully developed region.
Figure 6 gives the effect of the initial drop size on the extent of drop deformation in the entrance region
and drop breakup in the downstream side of the cylindrical tube (18).
Numerous investigations of laminar incompressible fluid flow along the entrance region
of a smooth circular pipe have been made both experimentally and theoretically since the work of Hagen in 1839 and Poiseuille in 1841.