Beautiful Bubble Texture in Guinness Beer

Abstract

We introduce how the bubble texture forms in a glass of Guinness beer. Bubbles rise in quiescent liquid due to the buoyancy; this phenomenon can be explained by Archmedes’ principle. However, after pouring Guinness beer into a pint glass, we notice that the bubbles go down. At the same moment, we can also observe a beautiful texture motion of a number-density distribution. Such a mysterious fluid motion can be observed when several hydrodynamic conditions are fulfilled simultaneously. This review introduces the motion of a single bubble, the instability of the gravitational flow associated with the gravitational separation, and the indicator of the clarity of the bubble separation. We address why bubble texture forms only in Guinness beer; paradoxically, we present the condition under which bubbles form texture in carbonated water.

graphical abstract