Mass Imbalance
 

I am simulating the flow through a cylinder with one inlet and two outlets as shown. The liquid is water. The boundary conditions are pressure inlet and pressure outlet. However, the mass flow rate at the inlet is less than 50% of the mass flow rate at the outlet. I exhausted all possibility and did not see anything wrong with my simulations. Can shed some ideas on what could be wrong?

Another question, when I increase the mass flow rate at the inlet, the mass flow rate at the outlets actually reduces. What could be the cause for this errors?

Thank you very much.