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zero-diffusion (constant gradient) boundary condition

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Old   July 26, 2011, 08:39
Default zero-diffusion (constant gradient) boundary condition
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Tom Witten
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Hi all,

I'm still relatively new to openfoam and despite searching through the tutorials, source code, and this forum have not been able to determine if the zero-diffusion boundary condition is available in openfoam or easily implemented.

Has anyone used this type of boundary condition in openfoam before?

Cheers,
Tom
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Old   July 26, 2011, 18:01
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Hi Tom, and welcome on board!

I believe that the BC you are looking for is zeroGradient. You just have to write " type zeroGradient;" within our patch.

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Old   July 27, 2011, 04:53
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Tom Witten
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Hi Cyp,

Thanks for the reply! What I'm looking for though is the zero-diffusion outlet boundary condition, not the zero-gradient boundary condition.

A zero-diffusion boundary condition is of the form d^2(phi)/d(n^2) = 0 where phi is a transported variable (e.g. a component of velocity, temperature, viscosity, ...). Typically when this condition is set at an outlet, the value of the node at a particular outlet position is calculated from the interior situated nodes as well as the first derivative which is some constant.

I think both fluent and cfx allow implementation of this boundary condition and wanted to know if openfoam also has this option as I would like to test openfoam for a few studies.

Cheers,
Tom
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Old   July 27, 2011, 07:35
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Anton Kidess
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Thomas, have a look at this thread: Second Derivative Zero - Boundary Condition
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Old   July 29, 2011, 04:59
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Thanks akidess, that's what I was looking for
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