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-   -   Simple steady incompressible pressureInlet flow does not converge (http://www.cfd-online.com/Forums/openfoam-solving/60181-simple-steady-incompressible-pressureinlet-flow-does-not-converge.html)

adamsview April 3, 2006 13:29

Hi everybody.... i'm trying to
 
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....

newbee April 3, 2006 14:37

hello! Im a beginner at OpenFO
 
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

adamsview April 4, 2006 02:47

well....i can't know exact val
 
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!

gzink June 6, 2006 09:04

Hi, I'm another new user of
 
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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