A fluid flow need some length to fully develop the velocity profile after passing through components like bends, valves, pumps, turbines or similar.
The entrance length can be expressed with the dimensionless Entrance Length Number as
El = le / d (1)
El = Entrance Length number
le = length to fully developed velocity profile (m, ft)
d = tube or duct diameter (m, ft)
Entrance Length Number for Laminar Flow
Ellaminar = 0.06 Re (2)
Re = Reynolds Number
Entrance Length Number for Turbulent Flow
Elturbulent = 4.4 Re1/6 (3)
The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.
The Darcy-Weisbach equation can be used to calculate the major pressure and head loss due to friction in ducts, pipes or tubes.
Heat transfer, pressure and head loss in a fluid varies with laminar, transitional or turbulent flow.
Calculate the volume flow discharged through a smooth-walled circular pipe.
Introduction and definition of the dimensionless Reynolds Number - online calculators.