Inspired by the way creamy Guinness seemed to spill less from the bar to the table, a team from Princeton University in New Jersey headed to the lab. In their own container they created three-millimetre bubbles from detergent—using a fine needle and pump—on the surface of a few different water-glycerol mixtures.
By either jolting or rocking the container side to side, they found that just five layers of bubbles in a foam matrix could decrease the height of the waves by a factor of 10, though this depends on container width and wall texture.
Their paper, published in Physics of Fluids, suggests the dampening effect is caused by the friction of the bubbles against the walls of the container—the kinetic energy is converted to heat. So it’s only bubbles around the edges of the container that make a difference.
It is hoped the research will have applications ranging from containing liquefied gases in tankers to propellants in rocket engines.