Centrifugal pump simulation
 

Hi, everyone!
I am a new to Solidworks Flow Simulation. Me and my friend try to simulate the performance of centrifugal pump with casing. The radius of rotating region is 1 cm bigger than the radius of impeller.
The boundary conditions are:
static pressure outlet=107409 Pa
inlet volume flow rate = 0.5175 l/s
We also have experimental data. The pressure drop for numerical and experimental data is the same but the experimetal torque is 2 times larger. We also have a problem with outlet mass convergence. The value of friction fluctuates with amplitude of 50% from friction averge values.The criterion was set manually to the value of 5e-4 kg/s which is about 0.1% from total mass flow rate. What might be the cause? Any help is appreciated
Thank you in advance