While you’ve probably worked it out by trial and error, scientists have proven the shape of the perfect fire.
In a study published in Nature Scientific Reports Adrian Bejan, a mechanical engineer from Duke University, shows that, all other variables being equal, the best fires are roughly as tall as they are wide at the base.
“Humans from all eras have been relying on this design,” said Bejan. “The reason is that this shape is the most efficient for air and heat flow.”
But Bejan says there is a deeper significance to all this.
“Our success in building fires in turn made it possible for humans to migrate and spread across the globe heat flow from fire facilitates the movement and spreading of human mass on the globe.”
He also claims that it is vindication of the “Constructal Law” Bejan proposed in 1996.
That postulates that movement – or “flow” – systems such as trees, rivers or air currents evolve into configurations that provide easier and easier access to flows.
The law has been used in improving design and maximizing efficiency of manmade systems.
“Our bonfires are shaped as cones and pyramids, as tall as they are wide at the base. They look the same in all sizes, from the firewood in the chimney, to the tree logs and wooden benches in the centre of the university campus after the big game. They look the same as the pile of charcoal we make to grill meat. And now we know why,” says Bejan.
Bill Condie is a science journalist based in Adelaide, Australia.
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