Behavior of foam: floating vs. submerged

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Discussion Overview

The discussion revolves around the behavior of foam, specifically focusing on the characteristics of bubbles in a column of foam, such as those found in soap bubbles. Participants explore various factors affecting the foam's structure and dynamics, including bubble geometry, rigidity, and the effects of external conditions like air pressure and drainage.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the differences in characteristics of bubbles at varying heights within a column of foam, suggesting factors like size and geometry may vary.
  • Another participant questions whether the foam is rigid or pliable and whether it is closed or open cell foam, noting that "foams" encompass a broad category of materials.
  • A participant specifies that they are considering soap bubbles, describing them as pliable and closed cell, while expressing concern about the complexity and cost of recommended literature.
  • One contributor proposes that the compression of a column of soap bubbles may resemble atmospheric compression, suggesting that bubble geometry could change from more spherical at the top to more asymmetric at the bottom, with surface width potentially increasing with depth.
  • Another participant highlights the dynamic nature of the foam system, noting that liquid drainage occurs and that bubbles at the bottom tend to be more spherical due to this drainage.
  • Additional questions are raised about the limits of neighboring bubbles in a soap bubble and the effects of sound waves and viscosity in a medium of soap bubbles.

Areas of Agreement / Disagreement

Participants express varying views on the characteristics of foam and the behavior of bubbles, indicating that multiple competing perspectives exist without a clear consensus on the dynamics involved.

Contextual Notes

Some assumptions about the nature of foam and the specific conditions affecting bubble behavior remain unaddressed, and the discussion does not resolve the complexities of foam dynamics or the implications of drainage.

Loren Booda
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Consider a cylindrical glass containing a column of foam. How do the characteristics (e.g. size, geometry, surface width, air pressure, etc.) of the bubbles near the top differ from those near the bottom?
 
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Andy,

Thanks for the specification. I was thinking about a foam of soap bubbles. Thus, I believe them pliable and closed cell.

The book you refer to is a bit pricey and extensive for my own needs here on PF, but I appreciate your recommendation in general.
 
I am under the impression that a column of soap bubbles compresses somewhat like the atmosphere does, exponential in character, but more visualizable.

The bubbles might form more complex geometry while progressing down the column -- more spherical near the top and more asymmetric near the bottom.

Also, bubble surface width on average would increase with increasing depth, to the extreme where there would be more soap volume than air volume.

Any contributions?
 
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I wonder if a soap bubble has a limit for the number of neighboring bubbles.

What would be the effect of a sound wave passing through a medium of soap bubbles?

What is the minimum viscosity for a medium of soap bubbles?
 

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