Physics researchers have developed a model to predict how a beer will foam. The researchers partnered with Einstein 1, a startup developing a new bottom-up tapping system in which the nozzle pushes up a movable magnet on the bottom of a glass to create a temporary inlet.

As the glass fills, the magnet moves back into place and the beverage is ready to drink. After repeatability studies to establish stable pouring conditions, they assembled a model that was then validated with experiments.

The group found that foam from Einstein 1’s tapping system is generated only in the first moments of pouring. Higher temperatures and pressures yielded more foam.

After that, beer’s liquid phase kicked in. Determined in large part by bubble size, the beer’s foam phase slowly decayed, taking approximately 25 times longer to fully fizzle out than it took the foam to form.

Next the researchers plan to study the effect of nozzle shapes, which will control foam formation, reduce consumption and pouring time and improve "the overall efficiency of the pouring process,” author Wenjing Lyu said. “By accurately simulating the foaming process, our model can help to improve the quality of the final product, reduce costs, and increase productivity in industries such as food and beverage, chemical, and others.”

The study, “Experimental and numerical investigation of beer foam” appears in the journal Physics of Fluids.