Despite the fact that fire is one of the oldest technologies in the history of mankind, building a campfire is not always an easy task. After collecting fuel, such as dry branches and cones, you need to decide exactly how to arrange them, and not only the safety of the fire, but also its strength depends on this. Popular Mechaincs Magazine figured out in how to kindle fires correctly in terms of mathematics.
A photo: TASSTASS
Adrian Bejan, a professor of mechanical engineering at Duke University in the United States, argues that the optimal shape for a campfire is a pyramid. He came to this conclusion seven years ago when he published his report in the scientific journal Scientific Reports. According to Bejan himself, he originally wanted to offer this unusual mathematical calculation as homework for his students.
The secret of the pyramidal shape lies in the scientific nuances that affect the behavior of fire: namely, thermodynamics and fluid dynamics. A bonfire is, in a sense, like a flaming piece of Swiss cheese. Between the stacked fragments of fuel (coal or wood) there are many gaps and holes that allow air to move. If your fire is built too tightly, oxygen will not circulate well enough to keep the fire going. If it is built too loosely, then the air will not gain the necessary energy to circulate at the right speed. However, as Bejan notes, the pyramid is not the only effective form. As long as the ratio of width to height is observed, it can be anything: a deviation in any of the parameters will lead to the fact that the fire will either burn out for a short time, or not ignite at all.
Mathematics can also be applied to fire safety. For example, rescuers often calculate the dynamics of forest fires using special simulators that take into account the landscape and wind. But, if we talk about an ordinary fire in nature, then the most reliable way to protect yourself from a fire is to build a fire in a fire pit.