# Flow of fluid : streamline flow and turbulent flow

## Flow of liquid

A flowing liquid may be regarded as consisting of a number of layers one above the other.
Flow of liquid can be divided into two categories
1. Streamline flow
2. Turbulent flow

### Streamline flow

Streamline flow is also known as laminar flow.

#### What is Streamline flow of liquids?

Flow of liquid said to be streamline if the velocity of a molecule, at any point, coincides with that of the preceding one.

Consider a liquid flowing through a tube of non uniform area of cross section. If all the molecules while at A, B and C posses value v1, v2 and v3 respectively, the motion is said to be streamline or laminar flow or steady flow or orderly

#### Characteristics of streamline flow

• The velocity of any molecule ,at a point, is independent of time.
• The layer of liquid in contact with the solid surface is at rest.
• The liquid in streamlined flow can be supposed to be in the form of parallel layers one above the other. This is also called laminar flow.
• Motion is governed by Newton's law of viscosity.
• In this flow, the loss of energy varies as the first power of velocity.
The path of molecule, in such a flow, is called a streamline.

#### Why two streamlines can never intersect each other?

A streamline may be strength or curved. Direction of motion of any molecule, at any point, on a streamline is given by the direction of tangent draw at that point. For this reason no two streamlines can ever intersect each other.

#### What is tube of flow?

A bundle of streamlines having same velocity of fluid elements , over any cross section perpendicular to the direction of flow, is called a tube of flow.

## Turbulent flow

#### Definition of turbulent flow

Whenever the velocity of a fluid is very high or it rushes past an obstacle so that there is a sudden change in its direction of motion, the motion of fluid become irregular, forming eddies or whirlpools. This type of motion is called turbulent flow.

A fluid moving in turbulent flow exerts greater thrust on an obstacle in its path.
It depends on how suddenly the direction of motion of fluid, is changed by the obstacles.
A comparative study of thrust on three different bodies is
A flat disc feels maximum thrust

Ball feels lesser

While a pin pointed obstacle feel minimum thrust

Here the motion of fluid remains streamlined. That is why the body is said to be possessing a streamlined shape.

This is all about streamline flow and turbulent flow. If you have any queries you can ask .

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