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. 
     
What is streamline flow of liquid

 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 
Streamline flow and turbulent flow

 Ball feels lesser 
Turbulent flow

 While a pin pointed obstacle feel minimum thrust 
Turbulent flow of liquid

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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