Science & Technology

Physics behind a bubble cascade formed in a glass of Guinness beer

The texture of Guinness beer foam in a pint glass. It features a creamy taste of small bubbles and attractive texture movements.Credit: Osaka University

Is the foam cascade formed only in a glass of Guinness beer?

Researchers at Osaka University and Kirin HD explain the physics that underpins the cascade flow of nitrogenized stout beer, as well as its application to water purification and pharmaceutical manufacturing.

Back in 1959, the Guinness brewery developed a system that radically changed the texture of draft beer. Currently, Japanese researchers have solved the physics of Guinness Cascade Flow. This will be widely applied in life science and environmental science technologies.

In a recently published study Physical Review E, Researchers at Osaka University have clarified why the nitrogen bubbles in Guinness draft beer flow like liquids.

Many freshly opened soft drink foam simply moves upwards according to Archimedes’ principle. Much of the appeal of the Guinness beer draft is the collective sinking and flow of bubbles, known as the “bubble cascade.” Brewers and researchers believe that this collective flow behavior must be related to how draft Guinness beer is distributed. Currently, collective physics remains unsolved, which is what researchers at Osaka University are working on.

Bubble motion trapezoidal glass

Foam movement in trapezoidal glass: Each drink (from left to right on each panel, Guinness beer, Heineken beer, champagne, cola, carbonated water) was poured into the trapezoidal glass.Credit: Osaka University

“Working and computational simulations in various laboratories helped to estimate the movement of individual bubbles, but only after the flow occurred,” said Tomoaki Watamura, the lead author of the study at Osaka University. Yes, the senior author states. “We are interested in predicting cascade flow through mathematical modeling, not the results of ex post facto experiments or simulations.”

To do this, researchers used numerical simulations to estimate fluid and bubble particles in cascade draft beer. The benchwork experiment consisted of a clear “pseudo-Guinness solution”, a mixture of ultra-small hollow particles in tap water, and a test of actual Guinness beer.

Particle concentration distribution

(A) Composition and snapshot of particle concentration distribution. (B) Comparison of the distribution of simulated particles (left) and Guinness beer foam (right) at the midpoint. (C) A snapshot of the bubble concentration wave formed by a pint glass (upper left), a cocktail glass (upper center), and a 1 ounce (30 ml) shot glass (upper right). Phase diagram of scaled velocity fluctuations (bottom). The shaded area corresponds to the general dimensions of glass.Credit: Osaka University

“The simulation results were consistent with the experimental data for a variety of glass sizes and other conditions,” explains Watamura. “We have developed the most successful simulation of Guinness beer cascade flow to date.”

Interestingly, the Cascade Bubble may not require nitrogenized stout beer after all.

“The diameter of the bubbles in the carbonated water and the volume fraction of the bubbles are poured into the approximate dimensions of a typical 200 liter drum with an inclination angle, which promotes the cascading of bubbles,” says Hideyuki Wakabayashi of Kirin HD. Says. “In addition, the movement of the associated fluid near the walls of the sloping container is related to the maintenance of product quality during brewing, suggesting an immediate application of our findings.”

In addition to demonstrating insights into optimizing brewing conditions, this study clearly applies to any task, including fermenters or cell cultures. Thus, the discoveries of researchers at Osaka University and Kirin HD could be used to meet a variety of needs, from industrial-scale cell culture to drug production and urban water purification.

Reference: June 7, 2021, by Tomoaki Watamura, Kazuyasu Sugiyama, Yuko Shimoto, Mihoko Suzuki, Hideyuki Wakabayashi “There is a possibility that not only stout beer but also a cascade of bubbles will be formed.” Physical Review E..
DOI: 10.1103 / PhysRevE.103.063103

Grant: Japan Society for the Promotion of Science

Physics behind a bubble cascade formed in a glass of Guinness beer Physics behind a bubble cascade formed in a glass of Guinness beer

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