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Problems with non-reflective boundary conditions

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Old   March 14, 2014, 14:33
Default Problems with non-reflective boundary conditions
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Hi Foamers,

I am new to openFoam and I am trying to use it to model the effects of a pressure wave exiting a tube into the open environment. At the moment this has been solved as an axisymmetric model.

I am using the timeVaryingUniformFixedValue boundary condition at the pipe inlet (with clamp for out of bounds) to create the pressure pulse which then propagates out of the tube.

There are a couple of problems I am having however, mainly concerning reflection of pressure waves:

1) I need to use a non-reflective BC at the inlet, however I am already using the timeVaryingUniformFixedValue BC here. Is there any BC which allows waveTransmissive to be used in conjunction with timeVaryingFixedValue, or something else that might be suitable?

2) Would rhoCentralFoam or rhoPimpleFoam be more suitable for this problem? rhoCentralFoam seems to be more stable and gives more realistic answers, but the flow is subsonic and it is a fairly weak pressure wave.

3) Implementation of waveTransmissive in the farfield gives the error "keyword inletOutlet is undefined in dictionary" for rhoCentralFoam. Any ideas why this might be? On top of this what would you use when solving with rhoPimpleFoam in place of waveTransmissive as I don't believe you can use a NRBC with a pressure based solver?

Any help would be greatly appreciated.


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compressible flow, rhocentralfoam, rhopimplefoam, wavetransmissive

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