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Simple steady incompressible pressureInlet flow does not converge

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Old   April 3, 2006, 13:29
Default Hi everybody.... i'm trying to
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Alessio V
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Hi everybody.... i'm trying to solve s "simple" pressure-pressure case of a incompressible newtonian liquid flow in a 3D domain. I'm using simpleFoam with pressureInlet and pressureOutlet. The problem is that i really can't reach any kind of convergence...it seems OpenFOAM can't initialize the U field. I have really strange outflows with very high velocity (e+6,e+7) after just 1 step (and increasing it going on)!!
I'm using a pressure of 413 at inlet (2.8 bar divided by 678 kg/m3), 0 at outlet and epsilon=0.02 and k=4e-4...it should give a velocity, close to the inlet, of about 0.09 m/s!!!
I've tried with a potential case first, to initialize...but not results are reached. I would like to try with a boundaryFoam too...but it is like it doesn't exist!!
Can anyone help me????

P.S.: i've decreased relaxiation factors and i'm using most upwind schemes. I've played increasing and decreasing by 1 or 2 orders the tolerances too....but nothing seems to become better....
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Old   April 3, 2006, 14:37
Default hello! Im a beginner at OpenFO
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hello! Im a beginner at OpenFOAM but I got a familiar (unreasonable high) answer when i had mixed up my patches for inlet and outlet i.e. i got correct results when selecting my U negetiv at the inlet.

just an idea
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Old   April 4, 2006, 02:47
Default well....i can't know exact val
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Alessio V
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well....i can't know exact values of velocity at every inlet node.... it should be calculated by the pressure exact value i'm imposing. I'll try to use an initialization of U at inlet with negative values following your idea, but i really would like to know HOW OpenFOAM initializes U field at pressureInlet boundary!
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Old   June 6, 2006, 09:04
Default Hi, I'm another new user of
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Greg Zink
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Hi,

I'm another new user of OpenFoam, seeing a similar problem. I am running an inviscid pipe flow with pressure bounds and my velocity keeps increasing as I iterate. It works with inlet, specifying a velocity, but I can't get it with pressureinlet. Any ideas?

Greg Z.
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