Error in flux at Fluent´s mixing plane calculation

ales

Hi, all; I calculate water turbine model and I am using Mixing Planes. I have two fluids and my settings are: pressure-outlet stator and velocity-inlet rotor (is periodic), Mixing under-relaxation 0.1, Underelax: momentum 0.5 and pressure 0.2, Discretization: Pressure – standard, Momentum, Tke, Tdr – second order, Solver – segregated, steady, Viscous – k-eps standard. It converges well but my problem is: I have solved(converged) solution but: Flux (Report fluxes) on stator's velocity-inlet (pressure outlet) is not the same as flux on rotor's velocity-inlet ! >> (Velocity magnitude on stator's pressure outlet is not the same as on rotor's velocity-inlet ! ) But Area is the same (area difference 0.2 %). Mesh on areas is quad. (for example: Stator(v-inlet,p-outlet) – flux – 160 kg/s vs Rotor(velocity inlet) – flux 163,5 kg/s. >>> error is 2 – 5 % ! ) Is it typical error of Mixing Plane model or should I use other boundary condition for downstream (Mass flow inlet, Pressure inlet)? Or should I use other settings or approach with Mixing Plane in order to decrease deviation in flow rate?? Thanks