Reynold's number is a pure number and it is equal to the ratio of the inertial force per unit area to the viscous force per unit area for a flowing fluid.
Reynold's number $K=\frac{v_{c} \cdot \rho \cdot r}{\eta}$
where $\rho=$ density of the liquid $v_{c}=$ critical velocity $\eta=$ coefficient of viscosity of liquid $r=$ radius of capillary tube Fact
(i) For pure water flowing in a cylindrical pipe, $K$ is about 1000 . When $0 < K< 2000$, the flow of liquid is streamlined.
(ii) When $2000< K< 3000$, the flow of liquid is variable between streamlined and turbulent.
(iii) When $K >3000$, the flow of liquid is turbulent.