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Fluid Filled Shell (Hollow Tube) Model

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Hello,

I am trying to model a water filled thin hollow tube as a shell. I have the material properties of the shell material and know the pressure boundary contitions at the two ends of this hollow tube. There is no inlet or outlet. The idea of the model is to see at what pressure differential the water starts to move inside the tube causing one end of the tube to deform.

I am having issues creating a model that runs and gives no errors because of the no inlet/outlet condition. Does anyone have any suggestions/tips?

Thank you!


3 Replies Last Post Jan 10, 2023, 12:59 p.m. EST
Dave Greve Certified Consultant

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Posted: 1 year ago Jan 9, 2023, 11:07 a.m. EST

In steady state, you cannot have a pressure difference without flow.

As always, posting a model along with a description of the problem might get you some useful advice.

In steady state, you cannot have a pressure difference without flow. As always, posting a model along with a description of the problem might get you some useful advice.

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Posted: 1 year ago Jan 9, 2023, 5:14 p.m. EST

Hi Dave, thank you for your response. I am attaching the model I am working on below. For clarification I am using 2D axisymmetric. The pressure (0.2Pa) on one end of the shell should cause the flow (that pressure comes from an external speaker - perhaps there is a better way to define it in the model).

From experiments we know what the measured pressure should be at the other end (0.0483Pa). Ultimately we want to match the displacement of the edge at this ends with our experiment.

Hi Dave, thank you for your response. I am attaching the model I am working on below. For clarification I am using 2D axisymmetric. The pressure (0.2Pa) on one end of the shell should cause the flow (that pressure comes from an external speaker - perhaps there is a better way to define it in the model). From experiments we know what the measured pressure should be at the other end (0.0483Pa). Ultimately we want to match the displacement of the edge at this ends with our experiment.


Dave Greve Certified Consultant

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Posted: 1 year ago Jan 10, 2023, 12:59 p.m. EST

There is no analysis step in the model.

The pressure point constraint does not do what you think it does. It sets the reference point for all pressure evaluations; it is not a source. You must have one (and only one) pressure point constraint.

It is not clear whether your problem involves a time-dependent input pressure, a constant pressure, or a sinusoidal source at a particular frequency. Your mention of a "loudspeaker" suggests the latter. In that case you may want to to be doing an acoustics calculation.

There is no analysis step in the model. The pressure point constraint does not do what you think it does. It sets the reference point for all pressure evaluations; it is not a source. You must have one (and only one) pressure point constraint. It is not clear whether your problem involves a time-dependent input pressure, a constant pressure, or a sinusoidal source at a particular frequency. Your mention of a "loudspeaker" suggests the latter. In that case you may want to to be doing an acoustics calculation.

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