Question

A flow of liquid is streamline if the Reynolds number is

• A. greater than 1000
• B. between 4000 to 5000
• C. less than 1000
• D. between 2000 to 3000

Answer 1

Answer: (C)

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.