A Brazilian scientist and teacher has shown how to apply physical laws and mathematical apparatus to everyday tasks that students can understand. He calculated and validated the ideal shape of a beer glass.
Previous research and plenty of anecdotal evidence suggests that beer drinkers prefer a cold beverage – usually as cold as possible. Many beer drinkers also like to drink their beer from a clear glass – it gives them the opportunity to keep track of the remaining volume and observe the colour, foam and bubbles.
Unfortunately, clear glasses tend to heat up the drink quickly. Because of this, beer glass manufacturers have developed a variety of designs intended to keep as much cold as possible for as long as possible. They have also adapted the shapes of the vessels to suit different types of drink to improve the olfactory experience of consumers.
Claudio Pellegrini, professor of thermal and hydrodynamic sciences at the Federal University of São João del Rey in Brazil, calculated the optimal shape of the glass to keep the beer in it cold for as long as possible. The paper is posted on the arXiv.org preprint server.
Pellegrini started this work to demonstrate to students how physics and maths can and should be applied in real life to solve everyday problems. Explaining the ‘practical relevance’ of the knowledge you learn is an important element of higher education. And a difficult one. It is good to give students close-to-reality examples and practical work, somehow related to their own existence, to keep them interested in their studies. It could be the task of optimally slicing a pizza, or calculating the perfect beer glass, as in this case.
The physicist did not consider external factors such as the heat of the hand holding the glass or the types of glass used. Instead, he focused on the shape of the glass to determine the rate of heat transfer.
The glasses in the calculations had an insulated base, ensuring that the temperature of the liquid only changed at the top and sides. The assumption in the study was also a fixed initial beer temperature and that the glass would have negligible thermal resistance. This scenario ensured that changes in heat transfer would be a direct result of the shape changes.
Through calculations, Pellegrini found that the best shape was a glass with a small base and an upward expansion, such as a pilsner glass.
The researcher noted that the truly best result for keeping beer cool would be a small vessel, a cut glass with a volume of up to 350 millilitres. In this case, the contents are drunk in one or two quick sips. However, the physicist insists that drinking beer in this ‘ugly’ way from mediocre glassware completely ignores the point of drinking.
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