Mystery of texture of Guinness beer: inclination angle of a pint glass is key to solution

Researchers demonstrated that the texture-formation in a pint glass of Guinness beer is induced by flow of a bubble-free fluid film flowing down along the wall of the glass, a world first. This phenomenon is found to be analogous to roll waves commonly observed in water sliding downhill on a rainy day.

from Top Technology News -- ScienceDaily https://www.sciencedaily.com/releases/2019/05/190507105603.htm