Difference between laminar flow and turbulent flow

Laminar flow

• In laminar flow, the fluid flows without any lateral mixing, cross currents and eddies.
• The flow is in the form of parallel streams which do not mix with each other.
• Hence this flow also called streamline flow or viscous flow
• Laminar flow occurs
• when the liquid viscosity is high
• liquid velocity is very low
• when the characteristic length is significantly small

Fig. Laminar flow

Turbulent flow

• It is characterized by eddies and cross-currents in a random direction.
• The fluid layers overlap with each and there will be lateral mixing.
• The velocity at which flow changes from laminar to turbulent is called as critical velocity.
• Turbulent flow occurs
• when the liquid viscosity is very low
• liquid velocity is very high

Fig. Turbulent flow

The Reynolds number (N_Re)a basic tool to predict the flow pattern.

• When N_Re < 2100   Flow is laminar
• When N_Re > 4000   Flow is turbulent
• When 2100<N_Re < 4000  Flow is transition flow where the flow is changed from laminar to turbulent