Perfect Shape for a Campfire - As Proven By Science
(This campfire might just be perfect. Credit: Guilherme Pedroso/Flickr)
Even if you’re not an Eagle Scout, you probably know that a good campfire should have the wood stacked to form a little pyramid.
Now we know exactly what shape that pyramid should have for the perfect blaze.
(Credit: Adrian Bejan)
All other variables aside, the base should be the same width as the height, says Dr. Adrian Bejan, a professor of mechanical engineering at Duke University. Bejan published his work this week in Nature Scientific Reports.
“The reason is that this shape is the most efficient for air and heat flow,” he says in a statement.
As Bejan’s handy chart shows, a wide, short fire won’t do as good a job at keeping you toasty at a chilly campsite.
Likewise, a tall, skinny fire also won’t do as good. It may seem like a pointy triangle of wood will get roaring hot, but it just doesn’t let channel the air and heat very well.
The hottest bonfire will be right in the middle, equally wide as it is tall.
“The fire is hotter when it ‘breathes’ better,” Bejan writes in his paper.
Bejan based his conclusions on his work on “flow” in natural systems, such as rivers and air currents. A shape that is equally wide and tall will offer the best flow, and thus the best fire. Bejan notes his findings hold true for large and small fires, and charcoal as well as wood. It also helps explain why people all over the world — from the ancient Egyptians to cowboys on the open range — build similar-looking campfires: They’ve all stumbled upon what turns out to be the most efficient design.
If the general conclusion seems simple, the science behind Bejan’s findings are complex.
“The body of fuel is a porous medium through which fluid flows because of the buoyancy effect due to low density (hot) fluid inside the body, and high density (cold) fluid outside the body,” he writes.
His calculations rely on models “black body radiation” and fluid viscosity, as well as esoteric concepts such as Darcy flow.
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