Type Of Flow MCQ - Practice Questions with Answers

• Steady flow-

  In this type of flow fluid Characteristics like Velocity, Pressure density, etc At a Point do not change with time.

  $$
  \text { I.e } \frac{d v}{d t}=0, \frac{d p}{d t}=0, \frac{d \rho}{d t}=0
  $$

• Unsteady flow-

  In this type of flow fluid Characteristics like Velocity, Pressure density, etc At a Point change with respect to time.

  $$
  \text { ।.e } \frac{d v}{d t} \neq 0, \frac{d p}{d t} \neq 0, \frac{d \rho}{d t} \neq 0
  $$
   

• Streamline flow- 

Streamline the flow of a liquid is the type of fluid flow in which each particle of the fluid passing through a point travels along the same path and with the same velocity as the preceding element passes through that point.

Or 

Streamline flow is defined as the path (straight or curved), the tangent to which at any point gives the direction of the flow of liquid.

For the above figure Path ABC is streamlined.

All the liquid particles passing through A, B, and C will have velocities as $V_1, V_2$ and $V_3$ respectively.

Property of streamlined flow-

1. The direction of velocity at any point on the flow line is along the tangent.

2. Two streamlines cannot cross each other.

• Laminar flow -

If a liquid is flowing over a horizontal surface with a steady flow and moves in the form of infinitesimal parallel layers of different velocities that do not mix with each other, then the flow of liquid is called laminar flow.

This type of flow is also referred to as streamline flow.

In this flow, the velocity of liquid flow is always less than the critical

velocity of the liquid.

• Turbulent Flow-
  When the velocity of liquid flow is greater than its critical velocity, then the motion of the particles of the liquid becomes disordered or irregular. Such a flow is called turbulent flow.

           In turbulent flow velocity of the fluid at a point is continuously changing in both magnitude and direction.

• Critical velocity-

Critical velocity is defined as the velocity of the liquid, flow up to which it's streamlined/laminar and above which its flow becomes turbulent.

• Reynold's Number-

Reynold's number is a number that determines the nature of the flow of liquid through a pipe.

Reynold's Number is defined as the Ratio of inertial force per unit area to the viscous force per unit Area for a flowing fluid.

It is denoted by  R_e which is given by

$$
R_e=\frac{\rho V \cdot d}{\eta}
$$

where $\rho=$ density of fluid
$\eta=$ coefficient of viscosity

V=velocity of fluid

d= diameter of the pipe

• Range of Reynold's number

1. If it lies Between 0 - 2000 then the flow of liquid is streamlined or laminar

2. If it lies Between 2000 - 3000 then the flow of liquid is unstable

              (means it changing from streamlined to turbulent)

3. If it is Above - 3000 then the flow of liquid is turbulent.