The mystery of the perfect pint of Guinness has been solved – it’s all to do with the shape of the glass.

Researchers at University of Limerick believe they have cracked how to serve the best pint of Ireland’s most famous beer.

They have concluded that the reason the bubbles sink is down to the shape of the glass – and they took their work to the pub in a bid to find out why.

Researcher Dr William Lee from the University of Limerick’s Mathematics Applications Consortium for Science and Industry told the Irish Times that the curious staff regularly drink Guinness on a Friday evening after math seminars.

“Although we were aware of previous work in the area, my colleague Prof Eugene Benilov pointed out there was a gap in the bubbles theory,” he said.

“While it was understood that the sinking bubbles were due to the small size of the bubbles and a circulation in the glass, there was no explanation of the origin of the current.”

The Irish Times reports that to fill in the theoretical gaps, the researchers used computational fluid dynamics and insight from a field trip to the pub with a measuring cylinder to find out the density of a stout beer.

“One of our colleagues tilted the cylinder when it was full of settling stout and we saw that the bubbles went down on the lower face and up on the higher face,” added Dr Lee.

“That told us that the slope of the glass was the key factor.”

The findings have now been presented in a paper by Lee, Benilov and Cathal Cummins at

They suggest the typical narrow-ended pint-glass shape has an important role to play in the sinking-bubbles phenomenon.

“We would be interested in seeing whether it is possible to redesign a pint glass to reduce the settling time. There could be wider implications for this,” said Lee.

“More generally, a lot of industrial processes involve bubbly flows so the research may find applications there.”

More details are available here.

Guinness Science - Sixty Symbols