which is Superior approach between TWO? In a pipe flow a 'fan' boundary condition OR a 'momentum source' boudary codition to pump the liquid water.

Maybe you should think about not reposting, but instead about rephrasing your question. That would - maybe - make it possible to answer.

Hi

I agree with the last coment your question is not a question!

Use acronames after writting the meaning of them.

So please rewrite your question, tell us about the diameter, Re, fluid, objective of the work, etc.

and made your title related to the problem!

Regards

Alex

A fan, I believe will simulate a fan with pressure loss? But I'm not 100% sure.

I don't recall a momentum inlet, but i do recall a mass inlet.

What are your objectives of this solution? If you are just doing a simple pipe flow analysis, then this is not a very important question to ask.

If the solution is more complicate, help us understand why.

A staight pipe havind diameter 1 in containing liquid-water, defining a 'velocity_inlet' & an 'outflow' is constucted. Two approches are going to be considered: 1) Anywhere two faces parallel to pipe-inlet are created heving some distance b/w them. splitting the pipe with these faces created three volmes. the middle volume is siad to be a separate vollume and in Fluent it is defined as 'momentum source'. 2) only one face is created parallel to pipe-inlet and that face is defined as 'fan' in Fluent.

I apologize, but I am still confused. I really don't understand what you are trying to do.