PROVIDENCE — Have you ever noticed how the bubbles in champagne stream in straight lines to the top of a flute glass? Or how that differs from bubbles in other carbonated beverages — like beer, soda, and seltzer — which disperse in all different directions?
A team of researchers at Brown University and the University of Toulouse in France have, and recently published their findings. Brown engineering Professor Roberto Zenit, the study’s lead author, said their research is based on a number of experiments, which help explain not only what gives champagne its distinct line of bubbles, but may hold “important implications for understanding bubbly flows in the field of fluid mechanics” that can be applied to other industrial uses.
Q. What made you want to study the bubbles in champagne — and other bubbly drinks?
Zenit: This started as curiosity-driven research. It was an excuse to study bubble dynamics, one of my core areas of research, which is the study of how bubbles move in liquids. Bubbles are prevalent in many industrial applications and natural phenomena. This particular study combines my two passions: bubbles in fluid mechanics, and my love for a bubbly beverage.
Q. What was known about the mechanics of these drinks before this experiment?
A. We explored the mechanics of what makes bubble chains stable, and if we could recreate them. [The gas bubbles that appear to rise rapidly to the top in a single file line are known as a “stable bubble chain.” When bubbles veer off to the side in other carbonated drinks, like beer, this means the bubble chain is “unstable,” Zenit explained.]
Part of enjoying one of these drinks is the small or larger bubbles that form when a drink is poured, which creates the chain of bubbles and their fizz. But the fluid mechanics involved are different depending on the drink and its ingredients. We wanted to know if we could make unstable bubble chains as stable as they are in champagne or prosecco.
Q. How did you investigate bubbles, and what did you find?
A. We found that the stable bubble chains in champagne and other sparkling wines occur because of ingredients that act as if they’re soap-like compounds called surfactants. These molecules reduce the tensions between the liquid and gas bubbles, making for a smooth rise to the top of a flute. [Zenit said this is what gives the flavor and uniqueness to the champagne or prosecco, too.]
To find out what makes bubble chains stable, we filled a small [plexiglass] container with liquid and inserted a needle at the bottom to pump it with gas to create different bubble strains. Then we gradually added surfactants or increased the bubble size.
We found that the larger the bubble, the more unstable bubble chains could become stable — even without the surfactants.
Q. Have you spoken to champagne or prosecco producers about this study?
A. Not yet, but that is one of my objectives. We can use these results to refine or improve the quality of sparkling wines or beers. Champagne is made in a specific part of France, and it’s a multimillion dollar business. They claim it can only be produced there because of its special properties, taste, and that’s probably correct. But you could potentially use these results to test out ways to make or perfect these drinks without actually having to do so in specific regions.
Q. How does understanding bubble dynamics fit into the creation of consumer products?
A. To me, not all, but some of our favorite carbonated drinks really come down to the science of the bubble. Some people enjoy the bite of carbonation. Others do not, so companies will add flavors or sugar to certain seltzers, sodas, and other fizzy drinks.
But the main actor or principal role of these drinks is the dynamics of the bubble and how bubbles change the perception of flavor. How bubbles move around in a glass is an important part to that conversation.
Q. Is it challenging to share your research on bubble dynamics with the public?
A. One of the most challenging parts of our job as scientists is making it accessible and understandable to those who are not technically trained. But if you want to understand the world around you, science is necessary. It can solve some of the challenges in your life.
Q. What other motivations are there to conduct studies in bubble dynamics?
A. Being in the Ocean State with new wind farms being developed, we know there’s one one way to protect the environment and marine life from the vibrations of these devices, and that is to add a curtain of bubbles at the base of these enormous windmills.
We also know bubbles emerge from the bottom of the ocean in some parts of the world. They’re cracks at the bottom of the ocean floor from which there are natural sources of methane (which is a gas that is produced naturally, and contributes significantly to global warming). It’s important to understand how fast and how much carbon dioxide or methane is coming out of the ocean just by natural sources in the form of bubbles. One way to do that is through studying bubble dynamics.
The Boston Globe’s weekly Ocean State Innovators column features a Q&A with Rhode Island innovators who are starting new businesses and nonprofits, conducting groundbreaking research, and reshaping the state’s economy. Send tips and suggestions to reporter Alexa Gagosz at firstname.lastname@example.org.