Archimedes number

Archimedes' number is named after the Greek Archimedes.

In viscous fluid dynamics, the Archimedes number (Ar) Do not confuse it with Archimedes' constant, π) is used when the motion of fluids is affected by density differences. 
It is a dimensionless number, the ratio of  gravitational forces to viscous forces. 

The relationship and has the form:

where:
  is the local external field (for example gravitational acceleration), ,
  is the density of the fluid, ,
  is the density of the body, ,
  is the dynamic viscosity, ,
  is the characteristic length of body, .

 References 

Category:Fluid mechanics
Category:Numbers
Category:Archimedes