Beer Bubbles

This is a video of beer bubbles generated by the IPA in my previous post. The release of the bubbles is described by Henry's Law. Once the bottle is opened, the gas pressure falls and beer is no longer in equilibrium with the vapor phase. Gas bubbles start to nucleate at sites in the glass harboring microscopic crevices which have trapped pre-existing air. Bubbles that have grown sufficiently buoyant then break off and head to the surface.

Unfortunately, my video rotator program does not seem to be functioning well so it is oriented sideways.

You will notice that the bubbles seem to start slow at the bottom but gain velocity as they rise. In fact, you can demonstrate this for yourself by freezing the video at any point and measuring the length of the bubble streaks as a surrogate for velocity. I did this for 20+ bubbles on a freeze frame and plotted the following graph.

The bubbles' velocities can probably be approximated using Stoke's velocity. However, this generalization will not take into account drag forces due to surfactants and other factors. I found this paper useful for getting a general intuition for bubble velocity physics.