It is normal to see people in different parties beer tapping a newly opened bottle of beer then stands back as the foam bubbles out on the floor. But have you ever wondered why it happens? Researchers explained the science behind it.

Researchers from the Carlos III University in Madrid, Spain and Universite Pierre et Marie Curie, Institut Jean le Rond d'Alembert, France, linked it to the “phenomenon of cavitation.”

Cavitation is the formation of foams or bubbles in a liquid caused by the application of forces which interact with the liquid. It usually happens when there are rapid changes in pressure resulting to a shockwave inside the bottle. The energy is immediately released as soon as the bottle is opened that is why we see beer foams. The higher pressure applied to the bottle before opening it, the higher the beer foam released.

Cavitation is usually observed in ship propellers which is the main cause of their engineering problems—it erodes the propellers.

“Buoyancy leads to the formation of plumes full of bubbles, whose shape resembles very much the mushrooms seen after powerful explosions," said lead author Javier Rodriguez-Rodriguez in a statement. "And here is what really makes the formation of foam so explosive: the larger the bubbles get, the faster they rise, and the other way around." He adds that this is because fast-moving bubbles entrain more carbonic gas.

Their research is the first to explain the beer foaming phenomenon. "We wanted to explain the extremely high efficiency of the degasification process that occurs in a beer bottle within the first few seconds after the impact," Rodriguez said.

They believe that their findings will help improve the designs of the engineering systems and explain natural phenomena such as the Lake Nyos disaster which took 1,700 lives when they suffocated with carbon dioxide.

The study was presented at the annual meeting of the American Physical Society (APS) Division of Fluid Dynamics.