Answer:
Critical Reynolds number is a number or the threshold or the limit at which the laminar flow changes to turbulent flow.
Step-by-step explanation:
It is basically the ratio of inertial forces to viscous forces and helps to predict if the flow is laminar or turbulent.
from the experiments, for flow in a pipe of diameter D, critical Reynolds number=2300
For Laminar flow: Reynolds number is less than 2000
For transitional flow: Reynolds number is in between 2000-4000, the flow is unstable
For Turbulent flow: Reynolds number is greater than 3500
Reynolds number is different for different geometries