Reply To: Incorrect velocity streamlines and observed velocities profile

[Rob]

With sliding mesh I'd expect a very correct result, mrf may smooth a little based on the approach. But.... For sliding you really need the mesh to be similar size on both sides of the interface: give the tip-interface proximity that's not the case here. So, either use a lot more cells in the whole model or increase the rotating zone size by a bit (technical term). 

Another but, given the relative coarseness of the mesh around parts of the rotating zone how well resolved is the flow between the fan and 1.5m below it? Ie has any higher speed been smoothed/diffused by the mesh?

Blade profiles will have a significant effect on the flow, otherwise why wouldn't you just use a pre-bought fan?