Ah, summer vacations. Thinking about them, you can almost smell the smoke from marshmallow-toasting campfires and backyard barbeques. What’s even better: Building those controlled blazes may require little thought, a new study shows.
Humans tend to build very efficient fires, perhaps unwittingly, says Adrian Bejan. He’s a physicist at Duke University. And he has crunched the numbers to back up his assertion.
Across cultures, countries and time, people have built fires in a similar way. They pile wood or other fuel into a pyramid or cone shape. Those piles tend to be about as tall as they are wide at the base, Bejan says. And there may be no need to learn this skill, he adds. People seem to do it instinctively. The question was why.
For a new study, Bejan made calculations of how air and heat flow through structures. Fires with proportions like those of common campfires produced the hottest flames for their volume of fuel, he finds. Fires lost more of their heat if they were relatively tall or short compared to their width, he now reports.
The calculations, appearing June 8 in Scientific Reports, suggest no scout handbooks are needed for those leisurely summer blazes.