Hi everybody,(adsbygoogle = window.adsbygoogle || []).push({});

first of all, sorry for any grammatical mistakes, I am a non-native English speaker.

So here is my concern,

the dimensionless (hydrodynamic) entrance length is defined as:

z+=zh/(Re*Dh)

,where zh is the hydrodynamic entrance length, Re is the Reynolds number, and dh is the hydraulic diameter of the duct.

If zh exceeds the total channel length L, do I have to assume zh=L for calculating z+??

Thank you very much

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# [Hydrodynamics/Heat transfer] Does the dimensionless entrance length have a certain value limit?

**Physics Forums | Science Articles, Homework Help, Discussion**