8 Replies Latest reply on Feb 12, 2015 2:07 PM by Bill McEachern

    Boundary Conditions do not match results

    Chris Phillips

      Hello, and thanks in advance for your responses.


      I ran a flow simulation where my boundary conditions did not match my results and am trying to figure out why this is. My model is a 30 leg header with water as the fluid. Each leg tees into a manifold that flows downstream where the flow terminates with a lid. The inlet of the legs are about 50 feet below the outlet. The bc is for a total mass flow rate for all 30 legs to be 24 lb/s and the outlet bc is an enviromental pressure of 50 psia.


      My results do not make sense: Only one leg has flow (.67 lb/s), which is equal to the outlet flow, but unequal to my bc of a total of 24 lb/s. All of my other legs have mass flow rates of 0. Also, my pressure drop from inlet to outlet was only about .5 psi. I know it should be significantly more as I have to overcome 50 feet of water head along with major and minor losses through pipe runs and tees.


      I think the issue is that I ran the simulation with a mesh setting of 1 and this took 6+ hours. I fear to run the simulation at a mesh setting of 3 or 4 would take exponentially longer.


      I will try adding goals to inlet and outlet flow rates, which seems like a redundancy. Any suggestions as to what I did wrong or how to speed up the simulation at higher mesh setting would be much appreciated.