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Old   November 26, 2009, 02:24
Default Porous Medium & Mass Flow Rate
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Hi all,

I have a case where I need to simulate an air conditioning unit which is consists of heat exchanger, bell mount, and grille. The air conditioning unit is placed in a room, while the outlet is attached to a long duct. since there is no fan in the unit, so a blower is put at the outlet of the duct in order to draw the air through the unit from room into the duct. In my boundary condition setting, I set the room as pressure inlet with static pressure =0, the heat exchanger as porous medium, and the outlet as mass flow inlet with reverse direction.
Now my problem is the simulation is converge nicely when i set a low mass flow rate at the outlet, but it is fluctuating when I set to a higher mass flow rate.
Anyone of you have any idea on this problem?

Thanks & regards,
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Old   November 26, 2009, 02:57
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in the second case, when the mass flow rate is more grater than first, the case converge?
if yes, there isn't problem you unenable from monitor resudal the absolut critorion of convergence and give more interete to stabilize your flow in outlet
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Old   November 26, 2009, 03:06
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Nope, the second case didn't converge, the residual started fluctuating at about e-03, and after about 300 iterations, it started goes up drasticly until e+08.
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Old   November 26, 2009, 03:18
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so the case diverge?
is it possible that you have a low number of mesh? i'm not very pratice with this program, so i would you resolve the problem with you. it is one eventuality to go gambit and remake the mesh but with a better precision.

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Old   November 26, 2009, 03:26
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I believe my mesh should be good enough already.
Anyway, thanks for your advice.
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