# inlet boundary condition based on specified water level

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 August 28, 2013, 15:37 inlet boundary condition based on specified water level #1 Member   Hale Join Date: May 2013 Posts: 53 Rep Power: 4 Hi, I am dealing with a two phase flow problem where I need to specify a constant water level for the inlet. I do not want to do it by specifying a velocity or flux. I tried to do it by specifying a hydrostatic pressure (rho*g*h) for p_rgh and zeroGradient for U but it blows up! Is there any way to specify the height of the water at the inlet? Thanks Hale

 August 29, 2013, 14:30 #2 Senior Member   Nima Sam Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,123 Blog Entries: 1 Rep Power: 14 well i guess you can do it via non-uniform alpha1 (i assumed you use interFoam as solver ) __________________ Training Course on OpenFOAM at (http://www.isme.ir/) My Weblog (http://openfoam.blogfa.com/)

August 30, 2013, 03:53
#3
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Hale
Join Date: May 2013
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Rep Power: 4
Quote:
 Originally Posted by nimasam well i guess you can do it via non-uniform alpha1 (i assumed you use interFoam as solver )
Hi Nima,

Thanks for the reply. Yes, I use interFoam. For the inlet where I need a constant water level I have defined alpha1=1 and zeroGradient for everwhere else. What did you mean with non-uniform alpha1?

August 30, 2013, 04:05
#4
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Nima Sam
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Location: Tehran, Iran
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well you can put a non-uniform alpha
something similar this :
Quote:
 y < h ? 1 : 0
where h is water level

you can used:

1- code stream
2: groovyBC

to create such nonuniform BC
__________________
Training Course on OpenFOAM at (http://www.isme.ir/)
My Weblog (http://openfoam.blogfa.com/)

 August 30, 2013, 04:16 #5 Member   Hale Join Date: May 2013 Posts: 53 Rep Power: 4 This is too complicated for me but would you please explain what will this non-uniform alpha1 do? I need a uniform water level at the inlet so why should I changed alpha1 to non-uniform?

 August 30, 2013, 04:41 #6 Senior Member   Nima Sam Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,123 Blog Entries: 1 Rep Power: 14 in your post #1, you said you want a constant water level!, so i assumed! a portion of your inlet fill with water! if the whole inlet is water! then specify the velocity or flux whats wrong then? __________________ Training Course on OpenFOAM at (http://www.isme.ir/) My Weblog (http://openfoam.blogfa.com/)

 August 30, 2013, 09:52 #7 Member   Hale Join Date: May 2013 Posts: 53 Rep Power: 4 The problem is that I'm simulating a real life problem where the flux is not known but the water level can be adjusted. Therefore I want to specify the water level in terms of hydrostatic pressure or something else that can allow the model to find the flux/velocity by itself.

 April 10, 2014, 11:18 Different water levels; BCs OpenFOAM #8 New Member   Join Date: Apr 2014 Posts: 3 Rep Power: 3 I have a similar problem. I have two water tanks connected by a pipe. The tanks have two different water levels. I want to keep this difference constant but I do not know the flow rate at the inlet and outlet. Therefore I should find the BCs that allows me to keep the water levels constant in the tanks. Any help? Thank you

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