What is Fluid Mechanics?
As the name implies, fluid mechanics is the study of fluids at rest (fluid statics) or in motion (fluid dynamics). The basic laws which are applicable to any fluid for analysis of any problem in fluid mechanics, are
- The law of conservation of mass
- Newton’s second law of motion
- The principle of angular momentum
- The first law of thermodynamics
- The second law of thermodynamics
Fluid mechanics, science concerned with the response of fluids to forces exerted upon them. It is a branch of classical physics with applications of great importance in hydraulic and aeronautical engineering, chemical engineering, meteorology, and zoology.
A fluid is a substance that deforms continuously under the application of a shear (tangential) stress no matter how small the shear stress may be. Because the fluid motion continues under the application of a shear stress, we can also define a fluid as any substance that cannot sustain a shear stress when at rest.
Click on the links given below to some important topics related to fluid mechanics that will be beneficial for aspiring civil engineers:
Key Concepts:
- Viscosity
- Various Types of Thickness of Boundary Layer
- Various Connections in Pipelines
- Types of Pressure
- Types of Motion or Deformation of Fluid Elements
- Surface Tension
- Siphon
- Shear Stress in Turbulent Flow
- Pressure Diagram or Prism
- Model Analysis
- Metacentre and Metacentric Height
- Heads of a Turbine
- Euler Equation of Motion Along the Streamline
- Efficiencies of Centrifugal Pump
- Draft Tube
- Cavitation
Applications of fluid mechanics
It has traditionally been applied in such areas as the design of canal, levee, and dam systems; the design of pumps, compressors, and piping and ducting used in the water and air conditioning systems of homes and businesses, as well as the piping systems needed in chemical plants; the aerodynamics of automobiles and sub- and supersonic airplanes; and the development of many different flow measurement devices such as gas pump meters.
Fluid Properties
Any characteristic of a fluid system is called a fluid property.
Fluid properties are of two types:
- Intensive properties- Intensive properties are those that are independent of the size of the system or the amount of material in it. For example, temperature, pressure, density etc.
- Extensive properties- Extensive properties are those whose values depend on the size or extent of the system. For example, total mass, total volume, total momentum etc.
Following are some of the intensive and extensive properties of a fluid system.
- Viscosity
- Surface tension
- Vapor pressure
- Compressibility and elasticity
What are the basic principles of fluid mechanics?
The basic fluid mechanics principles are the continuity equation (i.e. conservation of mass), the momentum principle (or conservation of momentum) and the energy equation.
Fluid statics:
Fluid statics is a branch of fluid mechanics that studies the behavior of fluids when they are at rest. It examines the forces and pressure that fluids experience and exert when they are not moving.
Fluid dynamics:
Fluid dynamics is the study of how fluids, such as liquids and gases, flow, and is a subdiscipline of fluid mechanics. Fluid mechanics is the study of the forces on fluids and their mechanics.
Online Courses for Fluid mechanics (CE):
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Recommended Books for Fluid mechanics
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- GATE-2025: Civil Engineering Previous Year Solved Papers
- ESE 2025: Preliminary Exam: Civil Engineering Objective Solved Paper Vol-1
- A Handbook on Civil Engineering
At MADE EASY, learning never stops! Engineering students can access Fluid Mechanics videos here to boost their knowledge and prepare effectively for engineering exams.
SSC JE 2024-25, Practice Programme | Fluid Mechanics
LIVE SSC-JE 2024-25 Practice Programme | Fluid Mechanics
FAQs:
1. What is viscosity in fluid mechanics?
Ans. Viscosity is the property of fluids by virtue of which they offer resistance to shear or angular deformation.
2. What is cavitation in fluid mechanics?
Ans. Vapor pressure of liquid may cause an unplanned or undesirable effect called cavitation.
3. Types of fluids in fluid mechanics?
Ans. The fluids are classified into following types based on shear stress variation with velocity gradient:
- Newtonian fluids
- Non- Newtonian fluids
4. What is the potential head in fluid mechanics?
Ans. In fluid mechanics, potential head, also known as datum head, is the energy in a liquid due to its position, or elevation, above a reference plane.
5 What are the different types of fluid flow?
Ans. Steady and Unsteady flow, Uniform and Non-uniform flow, One, Two and Three-dimensional flow, Rotational and Irrotational flow, Laminar and Turbulent flow and Compressible and Incompressible Flow.
6. What is Reynolds number in fluid mechanics?
Ans. Reynolds number, Re= Inertia force/ Viscous force
7. What is capillarity in fluid mechanics?
Ans. Capillarity is a physical phenomenon that describes a liquid’s ability to flow in narrow spaces, such as thin tubes or porous materials, without the help of gravity.
8. What is a venturi meter in fluid mechanics?
Ans. A venturimeter is a device that measures the rate of fluid flow through a pipe.
9. What is metacentre in fluid mechanics?
Ans. Metacentre in fluid mechanics is an imaginary vertical line that passes through the point of intersection between the vertical axis of the floating body and a vertical line passing through the new centre of buoyancy occurring under a very small hit given to the body.
10. What is pressure head in fluid mechanics?
Ans. In fluid mechanics, pressure head is the height of a liquid column that corresponds to the pressure the liquid exerts on the base of its container.
11. What is priming in fluid mechanics?
Ans. In fluid mechanics, priming is the process of filling a pump with fluid and removing air from the pump and suction line before starting it.
12. What is the centre of pressure in fluid mechanics?
Ans. In fluid mechanics, the center of pressure (CP) is the point on a body where the total effect of pressure acting on it can be represented by a single force.