Why does a beer bottle foam up after a sudden impact on its mouth?

TL;DR

This paper explains how a sudden impact on a beer bottle's mouth causes a series of pressure waves that induce cavitation and bubble collapse, resulting in rapid foam formation.

Contribution

It introduces a detailed physical mechanism linking impact-induced waves to foam generation through cavitation and bubble dynamics.

Findings

Impact generates pressure waves in the bottle.

Cavitation causes bubble collapse and daughter bubble formation.

Rapid bubble growth leads to foam creation.

Abstract

A sudden vertical impact on the mouth of a beer bottle generates a compression wave that propagates through the glass towards the bottom. When this wave reaches the base of the bottle, it is transmitted to the liquid as an expansion wave that travels to free surface, where it bounces back as a compression wave. This train of expansion-compression waves drives the forced cavitation of existing air pockets, leading to their violent collapse. A cloud of very small daughter bubbles are generated upon these collapses, that expand much faster than their mothers due to their smaller size. These rapidly growing bubble clusters effectively act as buoyancy sources, what leads to the formation of bubble-laden plumes whose void fraction increases quickly by several orders of magnitude, eventually turning most of the liquid into foam.