Chocolate fountains are magical. They are mini-Wonka factories that sit on a table and transform already delicious marshmallows, strawberries, and pretzels into marshmallows, strawberries, and pretzels with chocolate on them. Magic.
But a new study published today in the European Journal of Physics goes beyond the culinary gloriousness and focuses on how a chocolate fountain can be used to teach students about fluid dynamics, or how fluids move.
A chocolate fountain is ideal for explaining how fluids move because it sends the same fluid (melted chocolate) through a series of different conditions. The chocolate is piped up to the top, runs over a dome, and falls down from the dome towards the next layer in a curtain. In each of these three situations, the chocolate flows in different ways, making it a perfect way to introduce students to difficult concepts like non-Newtonian fluids.
As the chocolate gets piped up through the system it experiences pressure-driven flow as its forced upwards against gravity. Then, as it flows over the domes, the chocolate thins, providing a good introduction to ideas like lubrication theory, a complex topic that tackles what happens as a liquid flows over a solid. But the most interesting concept is when the chocolate falls down from the dome in a curtain. Strangely, the chocolate pulls inwards, a phenomenon caused in part by the surface tension of the liquid pulling the chocolate sheet towards the interior of the fountain. While some aspects of the chocolate fountain are already easily explained, the authors note that “at a research level, the falling sheet leaves the greatest opportunity for further work.”
“It’s serious maths applied to a fun problem.” an author of the study, Adam Townsend, said in a statement. “I’ve been talking about it at mathematics enrichment events around London for the last few years. If I can convince just one person that maths is more than Pythagoras’ Theorem, I’ll have succeeded. Of course, the same mathematics has a wide use in many other important industries – but none of them are quite as tasty as chocolate.”
So the next time you see a chocolate fountain, take a minute to think about the physics. Then, enjoy.