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Axisymmetric volume conversions: is pressure affected?

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Old   August 24, 2017, 12:25
Post Axisymmetric volume conversions: is pressure affected?
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Andrew
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Hi, I'm using a 2D axisymmetric model with a mass flow inlet and examining pressure between two different sized pipes. and the guide says that the axisymetric model works by assuming the volume is swept around the axis by 1 radian, and that reported quantities need to be multiplied by 2pi to get the values for the full 360 degrees volume.

So if I have a mass flow for the inlet divided by 2pi for the swept volume of 1 radian, for example 0.2kg/s --> 0.0318 kg/s, does this mean that the reported pressure should be multiplied by 2pi? So 600kpa becomes 3,769.9kpa? It seems a bit too much, I'm not sure how to do this. Or does the conversion not affect pressure? What values are and aren't affected?

Thankyou for your advice.
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Old   August 25, 2017, 08:05
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Sebastian Engel
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Dear Andrew,

for 2D axisymmetric case only quanities which are dependent from the circumferencial direction need to be converted, such as volume flow and mass flow.
However, hydraulic pressure is a unidirectional quantity of the fluid. It is not changing in a circumferencial direction for an axisymmetric case. On the contrary, the force (in axial direction) on a surface exerted by pressure is dependent by the circumferencial direction.

You might check out the fluid flow formulation for axisymmetric models in the tutorial manual.

Best regards,
Sebastian
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