[Orb]

What is the best way to model a fan inside of an open ended tube to air? I want the fan to do all the work to the fluid (e.g. no inlet/outlet conditions). Unless there is a way to apply boundary conditions so that they are essentially initial conditions. Or do I do this with transient analysis?

[emreg]

you have to use MRF. steady is enough.

make ur inlet B.C = pressure inlet..
and outler BC=pressure outlet...
then give atm pressure to both of them.

[Orb]

Thanks for your post. You are saying make the enclosure large enough to where the boundary conditions dont affect the fluid around the fan? Can you do this without boundary conditions? Similar to mixing in a tank?

[krisshoe]

To model a fan in a tube, you can make your tube a separate fluid zone, and define a momentum source within this zone. You can adjust the magnitude of the momentum source to obtain the flow rate that you desire. Alternatively, you can define an surface with a pressure jump condition, and adjust the pressure drop to match the flow you want.