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Can I impose 2 boundary conditions in CFX Pre?

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Old   November 6, 2006, 12:43
Default Can I impose 2 boundary conditions in CFX Pre?
  #1
Alexxx
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I've tried to input both pressure and velocity in the inlet of a pipe, but error message shown.

Is it acceptable to impose 2 or more conditions in CFX Pre, or do I have to create more than one domain?
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Old   November 6, 2006, 14:09
Default Re: Can I impose 2 boundary conditions in CFX Pre?
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opaque
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Dear Alexx,

If your flow is supersonic you must set both conditions. Otherwise, you will have an ill-posed problem.. You cannot set two boundary conditions for the same physics at the same boundary. Imagine trying to set the heat flux and the temperature at the same location..

If you explain what you are trying to model, other members can help you find out the proper set of boundary conditions..

Opaque

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Old   November 8, 2006, 10:35
Default Re: Can I impose 2 boundary conditions in CFX Pre?
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Alexxx
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Thx Opaque.

In fact I'm a beginner in CFX. I want to simulate that pressure gradient is constant along a circular pipe carrying laminar flow of water. I also want to see the velocity profile in the cross section in fully developed region.

If I have an analytical solution, is that no matter what properties I set as the boundary conditions, the result would be the same?
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Old   November 17, 2006, 02:28
Default Re: Can I impose 2 boundary conditions in CFX Pre?
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HekLeR
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In cfx 10 you need to use a translationally periodic domain inteface plus a momentum source to set the pressure gradient.

In cfx 11 you can use the pressure change/drop condition with translational peridocity.
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