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kyubi June 14, 2008 11:53

Hi! I've got a question about
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;

name Outlet_constant;
patchName Outlet;
triangulate false;



In the directory
there is the Ux list


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

type fixedValue;
value nonuniform List<vector>
(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?

ngj June 16, 2008 03:30

Hi It sounds like crossing

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

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,


kyubi June 16, 2008 08:31

Thank you Niels! I'll read th
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.


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