Correct Answer - Option 2 : less than 2000
The Reynolds Number:
The Reynolds number for pipe flow is defined as
\({R_e} = \frac{{\rho VD}}{\mu }\)
where D is the pipe diameter, V is the average flow velocity in the pipe, ρ is the density of the flowing fluid and μ is the dynamic viscosity of the flowing fluid. Re is a dimensionless number. Any consistent set of units can be used for D, V, ρ and μ, and will result in Reynolds number being dimensionless.
The generally accepted criteria for laminar flow and turbulent flow in pipes is decided based on Reynolds Number and it is given as follows:
For Re < 2000, it is laminar flow.
For Re > 4000, it is turbulent flow.
For 2000 < Re < 4000, the flow is in the transition region.
