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Boundary Conditions for Converging Pipe

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Old   March 5, 2009, 10:09
Default I'm testing OpenFoam for a sim
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Sami Lakka
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I'm testing OpenFoam for a simple pipe flow case which consists from inlet, sudden contraction and outlet. The flow is laminar and I use icoFoam-solver.

My B.C for U is fixedValue (1) for inlet and zeroGradient for outlet.

B.C for pressure is zeroGradient for inlet and fixedValue (0) for outlet.

I would expect the flow speed to increase in the contraction but it is the same as in the inlet. I'm probably making a stupid mistake with boundary conditions so could somebody point out my mistake so I can go and cry in the corner.
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Old   March 5, 2009, 10:23
Default Your BCs seem correct. What ab
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Jose Luis Santos
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Your BCs seem correct. What about the BC at the walls?

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Jose Santos
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Old   March 5, 2009, 10:36
Default Walls are fixed value 0 for U
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Walls are fixed value 0 for U and zero gradient for p.

Here is the complete B.C definition (for U):

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
inlet
{
type fixedValue;
value uniform (0.088419 0 0);
}

outlet
{
type zeroGradient;
}

beforeNozzle
{
type fixedValue;
value uniform (0 0 0);
}

afterNozzle
{
type fixedValue;
value uniform (0 0 0);
}

nozzle
{
type fixedValue;
value uniform (0 0 0);
}

frontAndBack
{
type empty;
}
}

And for p:

dimensions [0 2 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 0;
}

beforeNozzle
{
type zeroGradient;
}

afterNozzle
{
type zeroGradient;
}

nozzle
{
type zeroGradient;
}

frontAndBack
{
type empty;
}
}
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Old   March 5, 2009, 14:50
Default Could you post a picture of yo
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Jose Luis Santos
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Could you post a picture of your results? Its hard to figure out what could be wrong in your setup.

Regards,
Jose Santos
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Old   March 6, 2009, 05:10
Default I managed to solve this. It wa
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Sami Lakka
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I managed to solve this. It was an error in my paraFoam visualization. I hadn't chosen a time step when I loaded the case. Instead I just pressed accept when paraFoam loaded. When I selected a time step using the slider the visualization shows correct values. Whatever the logic is behind this, I don't understand it.
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