What is Reynold's numbeer? What is its significance?

Explanation

Reynold's number `R_e`: Reynold's number is a pure number which determines the nature of flow of liquid a pipe.
`R_e=(rho v d )/eta`
where
`eta`= coefficient of viscosity of the liquid .
`rho`= density of liquid
v= critical velocity of the liquid flowing through the pipe .
d= diameter of the pipe
Significance: `R_E` is dimensionless number and therefore, it remains same in any system of units .
the criitical Reynold's number for the onset of turbulence in the range 1000 to 10000,depending on the geometry of the flow. For most cases
`R_e lt 1000` signifies laminar flow.
`1000 lt R_E lt 2000` is unsteady flow.
`R_e lt 2000` implies turbulent flow.
Reynold's number describes the ratio of the inertial force per unit area to the viscous force per unit area for a flowing fluid.