There are many important questions that science needs to answer. Like how to cure cancer? What is the most effective way to combat climate change? And why does chocolate in the chocolate fountain pulls inwards rather than going straight downwards? At least now we know the answer to the last one.
UCL mathematics student Adam Townsend said that he wanted to address the question, because “chocolate fountains are just cool”, but also because they model some aspects of fluid dynamics. It turns out curtain of chocolate pulls inwards simply because of surface tension, but that required some work to figure out. The study relied on ‘water bells’, which have the same physics and can be simply built in any kitchen. You only have to fix a pen vertically to a tap with a small coin on top. This should form a simple bell-shaped fountain.
In order to understand the physics of the chocolate fountain, scientists followed motion of the chocolate throughout the process. They studied how the chocolate flowed up the pipe to the top of the fountain, over the plastic tiers that form the distinctive chocolate fountain shape and down as a curtain, which curiously pulls inwards because of surface tension.
Dr Helen Wilson, co-author of the paper, said: “both the chocolate fountain and water bell experiments are surprisingly simple to perform. However, they allow us to demonstrate several aspects of fluid dynamics, both ‘Newtonian’ which includes everyday fluids such as air, water and syrup, and ‘non-Newtonian’ which is anything with an underlying structure that can be built up or broken down by flow such as biological fluids (e.g. blood) and molten chocolate.”
It is very important to stress that although results seemed to be pretty obvious and chocolate fountain was chosen purely for fun, research does have some importance to science.
Scientists note that understanding the thin film flows in the chocolate fountain may help with other areas, such as lava flow on volcanoes, tear films in the eye, and extracting plasmas out of nuclear fusion reactors. Furthermore, it is a great way to encourage people’s interest in math and sciences, which is always a good thing. At the end of the day, the lead author is right – chocolate fountains are just cool.