Streamline Flow: Definition, Characteristics, Formula, Application & Class Notes

Streamline flow is a type of fluid motion in which the particles of fluid flow in parallel layers without disruption. In this type of motion, the fluid particles follow a steady path called a streamline. These paths never cross each other. Streamline flow is also known as laminar flow.

The key characteristics of streamline flow are:

Orderly Motion
The flow of Fluids is a smooth and well-defined path called streamlines. Their path do not cross each other.
Constant velocity at a point
The velocity of fluid at a given point remains constant with time.
No mixing of layers

Adjacent fluid layers flow over each other without crossing. This makes the flow smooth and predictable. 
Low-speed condition
When fluid flows slowly through a narrow tube, streamline (laminar flow) occurs. 
Reynolds Number
The flow of fluid particles is streamlined if the Reynolds number is less than 2000. 

Also Check:

The equation of Continuity is a basic principle in fluid dynamics that explains the conservation of mass in a flowing fluid. As per the equation, the mass of fluid entering through one end of the tube per unit time is equal to the mass of fluid leaving the tube per unit time.

Read More: NCERT Solutions for Class 11 & 12

Mathematical Form (for incompressible fluid): 

$A_1{v}_1=A_2{v}_2$

where,

• $A_1$  and $A_2$ are sectional areas of different points in the pipe.
• $v_1$  and $v_2$ are fluid velocities.

Explanation

1. Velocity increases the fluid flowing through a narrow pipe section.
2. Widen the pipe, velocity decreases.
3. The area and velocity product remains constant to conserve mass flow rate.

Streamline flow is used in science, engineering, and medical fields. The important applications of streamline flow are: 

1. Blood flow in arteries and veins:

• The blood flow in the human body is streamlined manner. The blood flow through smaller blood vessels ensures efficient and silent circulation. 

2. Oil and Gas Pipeline

• To reduce the energy loss due to friction and to maintain steady transport of fluids, streamline flow is preferred. 

3. Water flow in Irrigation Channels

• Streamlined water flow in agriculture ensures even distribution with no erosion or turbulence. 

4. Inkjet Printers

• The movement of ink droplets for precise printing is controlled through streamlined flow. 

1. Water flows through a pipe of diameter 4 cm at a speed of $0.3\mathrm{m}/\mathrm{s}$ . If the pipe narrows to 2 cm, calculate the new velocity, assuming streamline flow. Use the continuity equation.
2. For water ( $\rho =1000\mathrm{k}\mathrm{g}/{\mathrm{m}}^3,\eta =0.001\mathrm{P}\mathrm{a}\cdot \mathrm{s}$ ) flowing at $0.5\mathrm{m}/\mathrm{s}$  in a 3 cm diameter pipe, calculate the Reynolds number and determine if the flow is streamline or turbulent. [Hint: Use $Re=\frac{\rho vD}{\eta }$ .

Students can find here the CBSE NCERT Class 11 notes.

Students can find here the NCERT notes link for the complete chapter of Class 11 Physics.