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Pressure has no sense with periodic bc

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Old   April 9, 2015, 04:04
Default Pressure has no sense with periodic bc
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xab
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xabi
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Hi everyone,

I am simulating the flow through a tooth of an oil pump but I am having some problems when imposing periodic boundary conditions on the inlet and the outlet. The mass flow rate and velocity are normal and similar to the non periodic problem but the pressure contour has no sense

I have simplified my problem making it longitudinal instead of circular and make translational periodicity. The bottom wall has a movement of 2 m/s and 3 bar of pressure drop from inlet to the outlet

I attach some pics of the results I obtain with and without periodic conditions.

With periodic conditions
Pressure_periodic.jpg

velocity_periodic.jpg


Without periodic conditions:
pressure.jpg

velocity.jpg



Thanks for every help
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Old   April 15, 2015, 02:21
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xab
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Hello again,

I managed to solve it and if there is somebody with the same problem I hope this will help.

The problem is that when setting periodic conditions, the contours of static pressure don't show the pressure gradient introduced at periodic conditions. So if you want to show the contours with the real pressure you need to create a custom field function as p+Δp*x

Hope this is of any help

Xabi
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