# Quick help needed.....

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 March 13, 2010, 12:31 Quick help needed..... #1 New Member   Gary Burns Join Date: Feb 2010 Posts: 3 Rep Power: 9 Hi, Ive got a box half filled with water. It has a 1" Dia inlet at the bottom and a 1" Dia outlet at the top. (open to atomoshere) The water is being sucked out of the inlet at -2.76 m/s. im getting reversed flow at the outlet. Ive tried increasing the outlet pipe length, but had no success with reversed flow problems. any suggestions?? Thanks in advance

March 14, 2010, 10:09
#2
Senior Member

Sebastian Gatzka
Join Date: Mar 2009
Location: Frankfurt, Germany
Posts: 729
Rep Power: 13
Quote:
 Originally Posted by Gary Burns any suggestions??
Tell us more about your (pressure) boundary conditions.
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 March 14, 2010, 11:17 #3 New Member   Gary Burns Join Date: Feb 2010 Posts: 3 Rep Power: 9 Hi, Im solving the problem using VOF. inlet conditions - velocity = -2.97 m/s, Water volume fraction = 1 outlet-vent conditions - water backflow volume fraction = 0, mixture gauge pressure = 0 Im adapting a region and then patching in the water. Im also solving the problem with water being pumped into the box at +0.9m/s. This works fine. Could the problem be that air is being sucked into the box through the outlet?? Which is what would happen as it needs to replace the water being sucked out of the inlet. Thanks

 March 18, 2010, 13:57 #4 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 13 I'm not sure about the exact implementation of inlet and outlet boundary conditions, but does an inlet makes sense if there is something going out of the domain? __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

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