I remember from earlier post that your case was steady. In steady state, the ntotal mass flow rate in = total mass flow rate out. nThe difference should be minor, Less than 1-2% ... But you have to apply this to the total. i.e add all the mass flow in and all the out. nThe volue flow rate can change due to the density as you mentioned. This could be larger than the previous estimate .. like it can reach 5-10%.he is applying mass flow inlet, we discussed this in earlier post. Not sure about the outlet, but I am assuming it is pressure outlet.n