I have a simple analysis which consists of a large inlet pipe which branches off into three smaller outlets.  My solution goals are mass flow into and out of the system, but there is a 25% disagreement between what is coming in and what is leaving.  How can this be possible?  We are solving the navier-stokes equations right?  These by definition include continuity which requires mass flux to be zero.  Someone please tell me that I am doing something wrong and it's not an inherent flaw in the software.