Modeling the fan with a mass flow interface
 

To model a fan just with it's operating point in CFX , I chose the front face of the fan as an interface and specified the mass flow at the operating point by selecting the mass flow interface model in the additional interface models tab.

The fan is actually located in a domain with pressure inlets and pressure outlets and now the fan front face provides the suction of air it is therefore modeled as the mass flow interface with that mass flow as it would have at it's operating point.

Could some one please let me know if this is a valid approach.

This is a valid approach providing the pressure drop across the fan is the right one for the flow rate it is delivering.

What are you doing with the back of the fan?

I didn't specify the pressure drop at the interface but I just specified the mass flow at the interface and this is from the operating point data of the fan.

Please look into the attached image , it may not exactly depict my domain but it throws a better illustration.

As shown in the image I only know that the inlet and outlet are just pressure boundaries at atmospheric pressure no other information is available.

I'm very much particular in having both the inlet and outlet as pressure based boundaries.

Yes, this is a valid approach providing the fan stays at its operating point.

Finding fan curve
 

Hi I am quite new to CFD i am trying to find out the fan curve what did uptill now I made inlet duct 15 times of fan dia with pressure inlet (0.0 Pa), outlet duct 30 times of fan dia with pressure outlet (0.0 Pa) and I am giving fixed rpm to the rotating region in between. I am measuring pressure in inlet and outlet duct at a position 10 times of fan dia. but Still I didnt find the relevant pressure difference across the fan and also the solution is not converges

I would be very grateful if you people help me out

Sounds like an FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria

or this one: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F