convergency prob. in mass flow inlet-prs.out. bc.
 

i tried to simulate a solid propellant rocket. my model contains mass flow inlet at the grain surface and pressure outlet at the supersonic exhaust.i tried to solve the probleb by the density base (implicit and explicit both) but the continuity residual, dosnt converge more than 0.01 and mass flows at inlet and outlet dont balance. when i tried pressure based solver, my solution for continuity, converge about .001 and mass flows are some balance but not exat. do somebody model a solid propellant rocket ? can somebody help me to converge my solution by density base solver?