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Reference pressure
Posted 27 juil. 2015, 04:36 UTC−4 1 Reply
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I'm simulating air in a tube (laminar flow)
In 'laminar flow' section I've chosen 'incompressible flow' (I've got an italian version of comsol, so maybe it's not right this one th english option... anyway, i've chosen the incompressible option)
Then in 'reference pressure level' (I hope this is the english name) I've chosen pref = 1[atm]
Then I've put v = 0.045 m/, buil the mesh and so on.
In the picture you see the result
Isn't it strange? I'm expecting P = 1atm somewhere...!
Anyway, my problem is: I want the pressure to be 1 atm at the inlet. I absolutely need it to be 1 atm. So maybe choosing 1 atm in reference pressure level is not the correct way....
what should i do?
In 'laminar flow' section I've chosen 'incompressible flow' (I've got an italian version of comsol, so maybe it's not right this one th english option... anyway, i've chosen the incompressible option)
Then in 'reference pressure level' (I hope this is the english name) I've chosen pref = 1[atm]
Then I've put v = 0.045 m/, buil the mesh and so on.
In the picture you see the result
Isn't it strange? I'm expecting P = 1atm somewhere...!
Anyway, my problem is: I want the pressure to be 1 atm at the inlet. I absolutely need it to be 1 atm. So maybe choosing 1 atm in reference pressure level is not the correct way....
what should i do?
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1 Reply Last Post 16 août 2015, 17:16 UTC−4
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Posted:
9 years ago
Helo Giada,
I thin the pressure we obtain is in addition to the reference pressure. In my case I set the initial pressure as rho0*g_const*(Hbath-z) where Hbath is the height of the bath and tho0 is the initial density of the water or another liquid (in case you couple with heat transfer this density varies). I obtain up to 500-600 Pa which is the effect of a column of water 6 cm in diameter and 6 cm heigh, extracting the middle ball. But you have to consider it on the top of the other 101325 Pa from the atmosphere. As in real life, Comsol let you "feel" the extra pressure of something. The values I get using air instead of water ar three orders of magnitude smaller and so is the density so it makes sense. Your results might be correct!
Cheers!
I thin the pressure we obtain is in addition to the reference pressure. In my case I set the initial pressure as rho0*g_const*(Hbath-z) where Hbath is the height of the bath and tho0 is the initial density of the water or another liquid (in case you couple with heat transfer this density varies). I obtain up to 500-600 Pa which is the effect of a column of water 6 cm in diameter and 6 cm heigh, extracting the middle ball. But you have to consider it on the top of the other 101325 Pa from the atmosphere. As in real life, Comsol let you "feel" the extra pressure of something. The values I get using air instead of water ar three orders of magnitude smaller and so is the density so it makes sense. Your results might be correct!
Cheers!
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