[iahmedimtiaz]

In my system the geometry contains one impeller & two concentric cylinders which generates an annular section where the flow goes down and internal section where the flow moves up due to the impeller suction effect.

I have simulated the flow dynamics using one "Finite Element software package" .

Now, I am calculating the mass flow rate by "surface integral" at middle cut section of the object. There are two mass flow rates. Flow goes down by annuls section and comes up by inside cylinder.

Both flow rate supposed to be same based on mass conservation law.

But I am getting significant difference specially at high rpm. Is this because of finite element method? Please advice.