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Fully developed outlet BC

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Old   June 19, 2016, 13:31
Default Fully developed outlet BC
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Hello. I'm new to OpenFOAM so this question is a little bit silly. I need to set a constant velocity inlet and a fully developed outlet.
p
Code:
    inlet
    {
        type zeroGradient;
    }

    outlet
    {
        type fixedValue;
        value uniform 0;
    }
U
Code:
    inlet
    {
        type fixedValue;
        value uniform (0.0 0.4 0.0);
    }

    outlet
    {
        type zeroGradient;
    }
I have tried LES and DNS. But both of them will have a backflow. Does anyone know how to solve this problem?
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Old   June 20, 2016, 14:06
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Any one could give me some suggestions?
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Old   June 20, 2016, 16:31
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Do you mean you have backflow at the outlet and want to avoid it? Then inletOutlet might be what you looking for.
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Old   June 21, 2016, 02:31
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Yes exactly. So can you give me an correct example to set U and p? I looked up on the internet and found several different ways. But none of them is working.
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Old   June 23, 2016, 05:00
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xuegy, the outflow profile is determined by the shape of your domain. Your boundary conditions look fine. If you want to avoid backflow, you must make your domain larger, so that the large turbulence structures will not impair the outlet. Is this a pipe? Then make the pipe longer at the outlet...
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