Biot number
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The Biot number is a dimensionless quantity used in heat transfer calculations, named for the eighteenth-century French physicist Jean-Baptiste Biot. The Biot number is the ratio of the thermal resist
A temperature distribution chart with Bi on the x-axis
Convection
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Convection is the transfer of heat through the physical movement of fluids, where warmer, less-dense material rises and cooler, denser material sinks.
Thermal image of a newly lit Ghillie kettle. The plume of hot air resulting from the convection current is visible.
Painting of William Prout
Fireplace, with grate and chimney
This color schlieren image reveals thermal convection originating from heat conduction from a human hand (in silhouette) to the surrounding still atmosphere, initially by diffusion from the hand to the surrounding air, and subsequently also as advection as the heat causes the air to start to move upwards.