Motorized impeller simulation

What is the best approach to simulating a system (heatsink)where the airflow is provided by a backwards curved motorizedimpeller fan such as this one?

http://www.ebmpapst.us/allpdfs/R1G175.PDF

With axial fans it is easy to simulate the swirl. How does one doit with these?

Thank you,

-Martin
SolidworksFlow Simulation