[hamid1]

Hi

How much long should be the length of a pipe with velicity inlet/pressure outlet bc?
what about pressure inlet/pressure outlet,
please also consider a body inside the domain

Thank you
Hamid

[delaneyluke]

If you're asking about the extensions at inlet and outlet then generally use 5D for the inlet extension and 10D for the outlet extension, irrespective of your BC's

Regards
Luke

[hamid1]

Thanks for reply,
why these extensions should be added? what if the downstream regime dosnt show any change even after 2D ?

[delaneyluke]

The inlet extension is required so that a fully developed flow enters your pipe domain.
The outlet extension is required to avoid reversed flow at the outlet BC.

You can start with smaller extensions and then increase if the above criteria are not met.

Regards
Luke

[hamid1]

thanks for reply