I created an internal simulation for an axial fan with inlet and outlet ducting.  I would like to determine the flow rate generated by the axial fan by setting the environmental pressures at the inlet and outlet of the ducting.  When I set the outlet pressure to atmospheric pressure and the inlet pressure to a little below atmospheric pressure, set my fan to rotate in the direction it does in real life, the results show flow from my oulet to the inlet.  So the flow is reversed!  When I change the direction of rotation of the fan, the direction of flow does not change in the results.  Still backwards.  However, by swapping the inlet and outlet pressures, I get flow in the correct direction.  But now the pressure differential across the fan is backwards and does not reflect reality since a fan MAKES pressure.  What am I missing here in setting this up to reflect reality where my fan creates flow from a lower to a higher pressure?