Toast-worthy discovery: Scientists uncover the mystery of Champagne bubbles

The size of bubbles has a direct impact on their stability, and since bubbles in carbonated drinks are typically small, surfactants play a crucial role in producing straight and stable chains. While beer also contains surfactant-like molecules, whether the bubbles rise in straight chains or not depends on the type of beer. Conversely, bubbles in carbonated water are inherently unstable since there are no contaminants to facilitate their smooth movement through the wake flows created by other bubbles in the chain.

Implications for understanding bubbly flows

The study not only sheds light on the scientific explanation behind Champagne's straight-line bubbles but also has implications for understanding bubbly flows in fluid mechanics. The findings provide a general framework for comprehending the formation of clusters in bubbly flows, which can be applied in various fields of economic and societal importance. For example, the research can aid technologies that rely on bubble-induced mixing, such as aeration tanks in water treatment facilities, by providing insights into how bubbles cluster and how to predict their appearance.

The team conducted simple experiments that could be easily replicated even in a local pub. They filled a small plexiglass container with liquid and inserted a needle at the bottom to pump in gas and create different bubble chains. To observe the chains, they poured glasses of various carbonated beverages, including sparkling water, beer, and Champagne. The study explains why Champagne's bubbles rise in a straight line while other carbonated drinks produce unstable chains, and the researchers' straightforward experiments have unveiled the mystery behind Champagne's bubble chains, which can have significant implications for future research.

Study Abstract: 

Bubbles appear when a carbonated drink is poured in a glass. Very stable bubble chains are clearly observed in champagne, showing an almost straight line from microscopic nucleation sites from which they are continuously formed. In some other drinks such as soda, such chains are not straight (not stable). Considering pair interactions for spherical clean bubbles, bubble chains should not be stable, which contradicts these observations. The aim of this work is to explain the conditions for bubble chain stability. For this purpose, experiments and direct numerical simulation are conducted. The bubble size as well as the level of interface contamination are varied to match the range of parameters in typical drinks. Both factors are shown to affect the bubble chain stability. The transition from stable to unstable behavior results from the reversal of the lift force, which is induced by the bubble wake. A criteria based on the production of vorticity at the bubble surface is proposed to identify the conditions of transition from stable to unstable bubble chains. Beyond carbonated drinks, understanding bubble clustering has an impact in many two-phase problems of current importance.