Galileo number, Ga, is a dimensionless group representing a ratio of forces present in the flow of viscous fluids.
where g is acceleration due to gravity, ρ density of the fluid, η viscosity of the fluid, and L the appropriate linear dimension.
Note that
or Ga = Re × gravitationaiforce/viscousforce.
Galileo number is Archimedes Number with the particle density equal to that of the fluid.