Fluid Flow - Definition, Types, Example, FAQs
Fluid flow is a fundamental concept in fluid mechanics that describes the movement of liquids and gases. To understand fluid flow, it is important to know what a fluid is, how it behaves, and the different types of fluids. A fluid is any substance that can flow and does not have a fixed shape, such as water, air, or oil. Fluid flow occurs when an unbalanced force causes the fluid to move from one place to another. Depending on properties like viscosity, density, and compressibility, fluids can be classified into ideal, real, Newtonian, non-Newtonian, compressible, and incompressible types. This topic is highly important for school examinations as well as competitive exams like JEE Mains and NEET.
This Story also Contains
- What is Fluid?
- What is a Fluid Flow ?
- Types of Fluid Flow
- Equation of Fluid Flow
- Applications of Fluid Dynamics in Real Life
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What is Fluid?
Fluid is the matter of substances that do not have any fixed shape and are subjected to external pressure. The main feature of a fluid is its flowing ability. Now, let's see What is Fluid Flow?
Examples:
Water, air, oil, milk, blood, etc.
What is a Fluid Flow ?
A Fluid flow is known as the movement of a fluid from one point to the other. Fluid flow includes a fluid motion due to some unbalanced force. Until external unbalanced forces are applied to the motion of a fluid, a fluid will continue its motion.
According to the natural properties of a fluid, there are different types of fluid. Let's discuss them in detail.
Ideal Fluid:
An ideal fluid is defined as a fluid that cannot be compressed and also does not contain any viscosity. This is an imaginary fluid used only for mathematical calculations. Other than that, this fluid does not exist in reality. They have a constant density. They possess irrotational motion which has a smooth flow. They do not have any internal friction and have a steady flow.
Real Fluid:
All a fluids of the real world which contain viscosity and can be compressed to some extent are known as real fluids. They are also called practical fluids.
Real Fluid examples- Water, oil.
Newtonian fluid:
A Newtonian fluid is defined as a fluid which obeys the laws of Newton of Viscosity, where the shear stress is directly proportional to the velocity gradient.
Newtonian fluid examples- Water and Gasoline.
Non-Newtonian fluid:
These fluids are opposite to Newtonian fluid. This fluid does not obey the laws of Newton of Viscosity. Theor viscosity changes with applied shear rate.
Non Newtonian fluid examples- Ketchup, toothpaste, blood.
Incompressible fluid:
When a fluid is subjected to any kind of external force, the density properties of a fluid does not change, this kind of fluid is known as incompressible fluid. Incompressible fluid example- Water, oil.
Compressible fluid:
When a fluid is subjected to any kind of external force, the density properties of a fluid will change and this kind of fluid is known as compressible fluid.
Compressible fluid examples- Natural gas, steam, air.
Superfluids:
It is a special phase of matter with zero viscosity that can flow without losing any energy. It has the ability to flow through tiny pores without resistance.
Superfluids examples- Liquid helium at very low temperatures
Plasma:
It is the fourth state of matter. An ionized gas where atoms are split into free electrons and ions, making it highly conductive.
Plasma examples- Stars (like the Sun), fluorescent lights, and plasma TVs.
Types of Fluid Flow
a fluid flow is categorized into different types considering different properties like steadiness, viscosity, compressibility, rotational property, and so on. They are categorized as below-
Based on their steadiness:
The velocity of a fluid decides the steadiness of a fluid flow.
- Steady flow: When the velocity of a fluid is constant, a fluid flow is found to be steady.
- Unsteady flow: When the velocity of a fluid varies from time to time, a fluid flow is found to be unsteady.
Based on their Viscosity:
a fluid is classified into viscous and non-viscous fluid.
- Viscous fluid: The term Viscosity is known as the measurement of a fluid thickness and a fluid with the viscosity is known as viscous fluid.
- Non-Viscous Fluid: A fluid having no viscosity is known as non viscous fluid.
Based on their compressibility:
On the basis of Mach number, flows are classified into compressible and incompressible fluid.
- Incompressible fluid flow has the Mach number M < 0.3
- Compressible fluid flow has the Mach number M between 0.3 to 1
Equation of Fluid Flow
The mass flow rate of a fluid flow is defined as the rate of massive fluid movement through a unit area. It is considered to be movement of mass of fluid per unit time.
Mathematically, the mass flow rate of a fluid can be written as
$$
M=\rho A V,
$$
where,
- $\rho$ denotes the density of a fluid
- A denotes the area of a fluid cross-section
- V represents the velocity of a fluid flow
Thus, the equation infers that the mass flow rate of fluid is proportional to density, area, and velocity of a fluid.
Applications of Fluid Statics in Real Life:
There are many applications of fluid statics in real life, the main application is it is used in the calculation and measurement of pressure of liquid in the field of hydrostatics like finding the pressure of floating and submerged bodies, pressure of water flow in water dams and gates, and water flow pressure in some liquid storage tanks of homes.
Applications of Fluid Dynamics in Real Life
There are huge applications in fluid dynamics, Let us discuss the few applications below:
- It is used to calculate and find the different types of forces and moments in the field of aircraft,
- It is used to determine the mass flow rate of petroleum or other gases through pipelines.
- Even they are used to predict weather patterns,
- It is used to understand and analyse the nebulae in interstellar space
- The use of fluid dynamics also plays a role in modeling different fission weapon detonations.
Frequently Asked Questions (FAQs)
The study of fluid at rest and fluid in equilibrium state is known as hydrostatics or fluid statics.
Based on their properties, they are different types of fluid. They are listed below
Ideal fluid,
Real fluid,
Newtonian Fluid,
Non Newtonian Fluid,
Ideal Plastic fluid,
Incompressible fluid and
compressible fluid.
When the fluid is subjected to any kind of external force, the density properties of the fluid does not change and this kind of fluid is known as incompressible fluid. Incompressible fluid example: Water.
Incompressible fluid example: The liquids which have low compressibility like water, petrol, oil are examples of incompressible fluid.
Compressible fluid example: Air and Vapour have higher compressibility than other liquids, so they are the best examples of compressible fluids.
A Newtonian fluid is defined as the fluid which obeys the laws of Newton of Viscosity. Some Newtonian fluid examples : Water and Gasoline.
Fluid mechanics definition can be given as the branch of physics that deals with fluid statics and fluid dynamics. The subject which deals with the behavioural study on fluid and its forces are known as fluid mechanics.
Fluid is the matter of substances which do not have any fixed shape and are subjected to external pressure.They include liquids, gases, and plasmas.
Fluid flow includes the fluid motion due to some unbalanced force. Until external unbalanced forces are applied to the motion of the fluid, the fluid will continue its motion. The mechanics that deal with the study of fluid flow properties is known as fluid dynamics.