What makes champagne pop?

We’ve talked before at Cosmos about the chemistry and the physics of champagne bubbles. But what about the pop?

According to a team of French and Indian researchers, the fizz is hiding some surprisingly complex fluid dynamics. It involves a supersonic flow of gases, and the modelling used to map them could have applications in areas as broad as rocket launching and wind turbines.

“We wanted to better characterise the unexpected phenomenon of a supersonic flow that takes place during champagne-bottle uncorking,” says Robert Georges, a researcher at the Université de Rennes 1, France, and co-author on a paper describing the research, published in Physics of Fluids.

“We hope our simulations will offer some interesting leads to researchers, and they might consider the typical bottle of champagne as a mini-laboratory.”

18 frames of champagne cork leaving bottle labelled with timestamps, plume of gases slowly escaping
High-speed imagery of the champagne pop’s first fraction of a second – this one at 20 degrees Celsius. Credit: Gérard Liger-Belair

The current simulations build on experiments the researchers had previously done, which established that the pop in a champagne bottle is actually a series of shockwaves. The high-pressure gases, made by bubbles, are initially blocked by the cork but eventually escape the bottle at supersonic speed, causing tiny sonic booms.

In this paper, the researchers show that the waves form shock diamonds – patterns that are normally seen in rocket exhausts. Then, the symmetry of the bottle causes a crown-shaped supersonic expansion. A few milliseconds later, the pressure has dropped to a point that can no longer sustain the faster-than-sound speeds.

Read more: Oreology: the fluid physics of twisting Oreo cookies

“Our paper unravels the unexpected and beautiful flow patterns that are hidden right under our nose each time a bottle of bubbly is uncorked,” says co-author Gérard Liger-Belair, from Université de Reims Champagne-Ardenne, France.

“Who could have imagined the complex and aesthetic phenomena hidden behind such a common situation experienced by any one of us?”

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