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Non uniform Inlet BC

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Old   June 14, 2008, 12:53
Default Hi! I've got a question about
  #1
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Marco Zecchi
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Hi!
I've got a question about how nonuniform BC work.

I want to set a parabolic inlet velocity profile in a pipe. In order to get it, I set a case in which I impose a uniform Inlet velocity distribution (3 m/s) and, at the end of simulation, whit a sampleSurface at the Outlet, I get the parabolic profile.

The sampleSurfaceDict is as follow

surfaceFormat foamFile;

interpolationScheme cell;

surfaces
(
constantPatch
{
name Outlet_constant;
patchName Outlet;
triangulate false;
}

);

fields
(
Ux
);

In the directory
sampleSurfaces/<time>/Outlet_constant/scalarField
there is the Ux list

n
(
.
.
)

I use this list to set U in the startTime directory of the new case, so

Inlet
{
type fixedValue;
value nonuniform List<vector>
n
(
(Ux 0 0)
.
.
)
}

Everything seems to work fine, but if I try to compute the average velocity at the Inlet with pathAverage I get 2.96 m/s, even if at the outlet of the first case I get 3 m/s whit patchAverage !

Can someone explain me why?
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Old   June 16, 2008, 04:30
Default Hi It sounds like crossing
  #2
ngj
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Niels Gjoel Jacobsen
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ngj will become famous soon enoughngj will become famous soon enough
Hi

It sounds like crossing the river to fetch water ... look at this thread, where you directly can get a parabolic inlet profile.

http://www.cfd-online.com/OpenFOAM_D...es/1/2246.html

I cannot recall which I used, but at least the post from the 6th of September 2007, at 7:13PM should work under 1.4.1.

Best regards,

Niels
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Old   June 16, 2008, 09:31
Default Thank you Niels! I'll read th
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Marco Zecchi
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Thank you Niels!
I'll read the thread that you suggest in order to set a parabolic Inlet profile.
...but I would like to understand why my solution doesn't works like should.

Marco
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