Imposing gas and liquid mass flow rate BC for hyperbolic equations
 

Dear Friends
I am trying to solve a two-phase flow problem in which the mathematical model is hyperbolic. I use two-fluid model as a mathematical model. I have gas and liquid mass flow rate at the inlet and pressure at the outlet of the pipe. the model is in 1d. I dont know who can I impose this type of boundary conditions at the inlet. As you may know if I dont know pressure or density at the inlet I can not compute volume fraction and velocity of the phases so I can not compute conservative variables at the Inlet. Please let me know if you know any information in this field. You can help me if you introduce me a good reference.
cheers