An Archimedes number, named after the ancient Greek scientist Archimedes, to determine the motion of fluids due to density differences, is a dimensionless number in the form

where:

• g = gravitational acceleration (9.81 m/s²),
• ρ_l = density of the fluid,
• ρ = density of the body,
• μ = fluid absolute viscosity.

See also

Fluid dynamics
pi is also know as Archimedes constant.