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Old   March 13, 2010, 12:31
Default Quick help needed.....
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Gary Burns
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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
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Old   March 14, 2010, 10:09
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Sebastian Gatzka
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Quote:
Originally Posted by Gary Burns View Post
any suggestions??
Tell us more about your (pressure) boundary conditions.
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Old   March 14, 2010, 11:17
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Gary Burns
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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
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Old   March 18, 2010, 13:57
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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?
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