# Galileo Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Galileo number, abbreviated as Ga, a dimensionless number, also called Galilei number, is used in fluid dynamics to describe fluid film flow over walls.  It is a ratio of forces present in the flow of viscous fluids.  The Galileo Number is used in the momentum of heat transfer, viscous flow, thermal expansion.

## Galileo number formula

$$\large{ Ga = \frac{ g \; l^3 \; \mu^2 } { \rho^2 } }$$
Symbol English Metric
$$\large{ Ga }$$ = Galileo number $$\large{dimensionless}$$
$$\large{ l_c }$$ = characteristic length $$\large{ft}$$ $$\large{m}$$
$$\large{ \rho }$$  (Greek symbol rho) = density $$\large{ \frac{lbm}{ft^3}}$$ $$\large{ \frac{kg}{m^3}}$$
$$\large{ g }$$ = gravitational acceleration $$\large{ \frac{ft}{sec^2}}$$ $$\large{ \frac{m}{s^2}}$$
$$\large{ \mu }$$  (Greek symbol mu) = viscosity $$\large{\frac{lbf - sec}{ft^2}}$$ $$\large{ Pa - s }$$