The reason behind why beer turns foamy when one bottle is bumped against another is now revealed by a team of researchers.
Scientists at Universidad Carlos III de Madrid (UC3M) has revealed the physical phenomenon and said that it is a process with three well-defined phases.
Javier Rodriguez, professor in UC3M's Department of Thermal and Fluids Engineering said that expansion and compression waves appear in the first phase, which causes the gas cavities (bubbles) to burst at the bottom of the bottle.
Afterwards, small balls of foam are formed because the bubbles break into even smaller ones, and as they weigh less than the liquid surrounding them, these bubbles move to the surface so rapidly that the final result is similar to an explosion.
According to the study, which was carried out in collaboration with the Institute Jean le Rond D'Alembert and the Universite Pierre et Marie Curie, the foam appears because of high concentration of carbon dioxide in carbonated beverages.