Research- Magic behind chocolate fountains finally explained

Watching delicious gooey chocolate pour down chocolate fountains is fun, but how many of us actually understand how they work?

A mathematics student has worked out the secrets of how chocolate behaves in a chocolate fountain, answering the age-old question of why the falling ‘curtain’ of chocolate surprisingly pulls inwards rather than going straight downwards.

“Chocolate fountains are just cool, aren’t they!” says Adam Townsend, an author on the paper, based on his MSci project. “But it’s also nice that they’re models of some very important aspects of fluid dynamics.”

The conundrum of the converging curtain was solved by looking at some classic work on ‘water bells.’

“You can build a water bell really easily in your kitchen” says Helen Wilson, the other author of the paper, and supervisor during Townsend’s MSci project. “Just fix a pen vertically under a tap with a 10p coin flat on top and you’ll see a beautiful bell-shaped fountain of water.”

The physics of the water bell is exactly the same as the falling curtain of chocolate; and the reason the chocolate falls inwards turns out to be primarily surface tension.

They also looked at the flow up the pipe to the top of the fountain, and the flow over the plastic tiers that form the distinctive chocolate fountain shape.

The researchers were also pleased to see that their work allowed them to engage with the public.