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where is Reference Level

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Old   June 5, 2013, 10:18
Default where is Reference Level
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Hello.
I want to model a free surface channel.
i am using "Open channel flow" option in fluent but when i am starting the solver and its done there is no any fluid into the model (there is just air).
my question is: where is the reference level in defining pressure inlet and pressure outlet of channel. please see attached images
thanks
Attached Images
File Type: jpg reference level.jpg (34.6 KB, 11 views)
File Type: jpg boundary1.jpg (70.8 KB, 9 views)

Last edited by flow_CH; June 6, 2013 at 04:43.
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Old   June 5, 2013, 10:51
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Probably you haven't patched the volume fractions of water and air properly. Have a look at the VOF tutorail in FLUENT

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Old   June 5, 2013, 11:11
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Quote:
Originally Posted by oj.bulmer View Post
Probably you haven't patched the volume fractions of water and air properly. Have a look at the VOF tutorail in FLUENT

OJ
thanks for your reply.
i read all fluent user guide but i don't understand what the patch is? what parameters i should define in patch for open channel flows.
I think my problem is in reference level.
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Old   June 6, 2013, 06:44
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You need to mark the registers where the fluid exists, and during initialization, set the value for volume fraction for the registers as 1. It's only then that you will have two fluids with volume fractions 1 in different regions, separated by the interface.

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Old   June 6, 2013, 09:29
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i know that. my question is: where is reference level in defining free surface and bottom of channel in OPEN CHANNEL FLOW option.
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Old   June 6, 2013, 10:58
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Well the reference level should be any arbitrary point, probably determined by the origin of your geometry. Just make sure that you give appropriate signs of the levels such that:
"free surface level" - "bottom level" = height of open channel flow

Does this help?

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