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Boundary Conditions do not match results

Question asked by Chris Phillips on Feb 12, 2015
Latest reply on Feb 12, 2015 by Bill McEachern

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.

 

-Chris

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