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## Mathematicians Show Why Bubbles Sink in Nitrogen-Infused Stouts55

SicariusMan writes "The age old question: do Guinness and other stouts' bubbles really sink, or is it an optical illusion? Well, some mathematicians have figured it out." Full paper via arXiv; From the article: "To analyze the effect of different glass shapes, the mathematicians modeled Guinness beer containing randomly distributed bubbles in both a pint glass and an anti-pint glass (i.e., an upside-down pint). An elongated swirling vortex forms in both glasses, but in the anti-pint glass the vortex rotates in the opposite direction, causing an upward flow of fluid and bubbles near the wall of the glass."
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## Mathematicians Show Why Bubbles Sink in Nitrogen-Infused Stouts

• #### late to the party (Score:5, Informative)

by Anonymous Coward on Wednesday May 30, 2012 @01:33PM (#40157313)

The Australians figured it out 12 years ago

http://science.slashdot.org/story/00/01/11/2156213/why-bubbles-in-guinness-fall

• #### American fluid dynamicists did it first! (Score:5, Informative)

on Wednesday May 30, 2012 @01:37PM (#40157361)

Twelve years ago an almost identical paper was on the office wall of a chemical engineering professor I had in college. I'm mostly kidding with my subject line - I expect there's novelty in the new paper and just want to point out that this has been used as a model system (probably many times) before now.

• #### Re:Is it replicatable? (Score:4, Informative)

on Wednesday May 30, 2012 @02:58PM (#40158509)
It's not because they're stouts, it's because nitrogen is used in making certain stouts (in this case, the title was better than the summary). Non-nitrogen stouts won't work. For example, Left Hand Brewery has a Milk Stout and a Milk Stout Nitro; only the Nitro has the cascade. Unless you find a nitrogen lager, there's really no experiment to be had.
• #### Re:Is it replicatable? (Score:4, Informative)

on Wednesday May 30, 2012 @03:08PM (#40158649)

Boddington's pub ale uses nitrogen, and it exhibits the same behaviour as Guinness.. it's interesting to see the effect in a clear fluid

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