In viscous fluid dynamics, the Archimedes number (Ar), is a dimensionless number used to determine the motion of fluids due to density differences, named after the ancient Greek scientist and mathematician Archimedes.
The Archimedes number is applied often in the engineering of packed beds, which are very common in the chemical processing industry.
It involves spraying a liquid into a bed packed with the solid to be coated.
A fluidizing gas fed from the bottom of the bed causes a spout, which causes the solids to circle linearly around the liquid.
Testing with such models found that Archimedes number is a parameter that has a very large effect on the minimum spouting velocity.