Find the Reynolds number (R) for liquids flowing through cylindrical pipe, wherein V is velocity of the liquid, ρ is density of the liquid, η is coefficient of viscosity of the liquid and D is diameter of the pipe.

The correct answer is option 2):(R = V ρ D / η)

Concept:

• Reynold's number: It is a pure number that determines the nature of the flow of liquid through a pipe. I
• t is defined as the ratio of the inertial force per unit area to the viscous force per unit area for a flowing fluid.
• Reynold's number is written as N_R.
• \({N_R} = \frac{{{\rm{Inertial\;force\;per\;unit\;area\;}}}}{{{\rm{Viscous\;force\;per\;unit\;area}}}}\)
• \(R_e =\frac{ρ V D}{η}\)
• V is the velocity of the liquid, ρ is the density of the liquid, η is the coefficient of viscosity of the liquid and D is the diameter of the pipe.