Reynolds number: The Reynolds number (Re) helps in the prediction of flow patterns throughout various fluid flow scenarios. There are two forms of flow: laminar flow and turbulent flow.
The Reynolds number tells us whether the flow is laminar as well as turbulent. Laminar (sheet-like) circulation dominates flows at low Reynolds numbers.
The flow appears to be turbulent at different (excessive) Reynolds numbers.
The ratio of inertial forces to viscous forces defines the Reynolds number.