A dimensionless number
used in fluid dynamics
as a measure of the ratio
forces to inertia
l forces, often written in terms of a pressure difference, Δp.
EU = p / (ρ v2)
p = pressure (or Δp = pressure difference), ρ = density, v = velocity
The Euler number was named for the famous Swiss mathematician Leonhard Euler. Some form of the Euler number is usually found in problems where pressure (or pressure differences) is important.
Two other variants of the Euler number (both dimensionless) are:
Pressure coefficent = Δp / (½ ρ v 2)
and the Cavitation number.
also see Dimensionless numbers
and Buckingham Pi Theorem