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implementation of constant water levels as boundary conditions

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Old   October 6, 2015, 11:19
Default implementation of constant water levels as boundary conditions
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horn
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Hi,

I want to create a 3D case of two communicating vessels with a water level difference, which are connected by a siphon. I have set this model up with snappy hexmesh (see attached figure). My interest lies in the flow speeds through the siphon as a result of the implemented water level difference.

Due to the flow the water level in the left vessel will decrease, while the level in the right vessel will increase. This is however something that I do not want because I am purely interested in the flow between those vessels given the current water level difference.

My question is: how can you set up your model (boundaries) in a way that water flows through the siphon due to the difference in energy level, while the water level is kept constant in both vessels?
I guess the solution has to do with adding the correct amount of water to the left vessel and substracting it from the right vessel based on the flow in the siphon.

Does anyone have an idea regarding this problem?

Geerten
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File Type: png Communicating_Vessels.PNG (57.6 KB, 27 views)

Last edited by horn; October 7, 2015 at 10:07. Reason: added the figure
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Old   October 12, 2015, 16:19
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Jerome Berryhill
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Just from a physics POV, what you really want is the flow due to a constant pressure. The fact that that pressure is generated by a difference in water levels is irrelevant.
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Old   October 12, 2015, 17:45
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Thinking about it further, what you want to know is flow as a function of pressure. But iwith OpenFOAM, it is probably easier to set the flow, and calculate the pressure. So, run a series of simulations at increasing flow, until you get one where the pressure difference corresponds to the level difference you are interested in.
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boundary conditions, constant boundary, dependend boundary, open channel

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