Laminar and Turbulent Flow

Laminar Flow

• In laminar flow fluid particles moves in a  straight line which is parallel to the direction of fluid flow. In this flow, flowing path of fluid never intersect each other. 
• Laminar flow occurs at lower velocities of fluid particles and at low velocities, the fluid tends to flow without mixing. 

• In laminar flow the velocity of the fluid is constant at any point in the fluid.
• In laminar flow we can say that one fluid layer just slides on adjacent fluid layer without lateral mixing
• In turbulent flow, the fluid moves in an unpredictable manner.
• Turbulent flow occurs at higher velocities.
• It must be noted that when the viscous force are dominant (slow flow, low Reynolds Number) they are sufficient enough to keep all the fluid particles in line, then the flow is laminar.

Turbulent Flow

• In turbulent flow fluid particle move on a irregular path with mixing each other.

• In this type of flow there are rapid variation in velocity and pressure of fluid
• When the inertial forces dominate over the viscous forces (when the fluid is flowing faster and Re is larger) then the flow is turbulent.

Transition Flow

It occur in between laminar and turbulent flow. Generally When fluid start to changing its behavior from laminar flow to turbulent flow then in between these two flow Transitional Flow occurs.

Effect of  Reynolds Number

    Behavior of flow of fluid can be also identified from the value of Reynolds Number

Based on the diameter of the pipe It is found that (but it is not necessary ) flow in a pipe may be laminar if the Reynolds Number is less than 2100 and is turbulent if it is greater than 4000. 

• For the higher value of Re greater contribution of inertia effect/force then it is turbulent flow.
• For the lower value of Re greater contribution of viscous stress/force then it is laminar flow.