A model for flow in a Farrel Continuous Mixer based upon cylindrical coordinate hydrodynamic lubrication theory is presented. Pressure and flux fields over the rotor surface are calculated. The pumping characteristics of the various sections of the machine rotors were calculated. Generally Farrel Continuous Mixers are operated under starved conditions. Calculations are presented for continuous mixers operating under starved conditions. Pressure and fill factor profiles are determined. Fill factors are predicted to be increased by increasing throughput, increasing exit gate pressure and reducing screw speed.