A Basic, Idiot’s Guide to Fluid Mechanics …and its role in our lives

  • In laymans terms the study of the fluid movement (flow) is known as Fluid Mechanics
  • There are three branches of Fluid Mechanics - Fluid statics, Fluid kinematics and Fluid dynamics covering everything from buoyancy to pneumatic pumps
  • In 250 B.C. Archimedes developed the principles of buoyancy leading to the development of sea vessels
Fluid mechanics: Liquid and gas are termed as fluid, and they can take the shape of any container

Liquid and gas are termed as fluid, and they can take the shape of any container

Fluid collectively represents liquid and gas, and the study of the movement (flow) of fluid is known as “Fluid Mechanics”. This is one of the oldest sciences which our ancestors tried to decipher. As “homo sapiens” started farming and living together, they saw the need to transport water (and later on sewage). Thus, began the study of Fluid Mechanics leading to Archimedes (250 B.C.) developing the principles of buoyancy. This later aided in the development of sea vessels.

Anything and everything that you see around you can be classified into three categories:

  1. Solid
  2. Liquid
  3. Gas

A very loose definition of them is as follows:

  • Anything that cannot change its shape is termed as solid
  • Liquid and gas are termed as fluid, and they can take the shape of any container

The primary difference between liquid and gas is that liquid is almost incompressible whereas gas can be compressed. The laptop/mobile that you are looking at while reading this article is solid, the coffee on the table is liquid and the air you breathe is in gaseous form.

Fluid mechanics - gas liquid flow

Branches of Fluid Mechanics

To easily understand the problem at hand, Fluid Mechanics has been further divided into three different segments. This segmentation is based on the status of fluid under study (i.e. if it is static or moving).

Fluid statics

This is the study of fluid when it is at rest and helps us understand buoyancy (floatation of objects on fluid). For most applications, we can consider the atmosphere around us at rest, and hence can understand the change in pressure with height. The same can be assumed for the ocean and fluid statics can be used to measure the fluid pressure a submarine has to withstand under-water.

Fluid kinematics

Fluid kinematics is the study of fluid in motion without considering the force that causes the motion. It helps us in understanding the behavior of fluids in a system where linear and turbulent fluid flow can drastically change this. For example, understanding the behavior of air at the tip of an aircraft wing can help us in optimum design of wings.

Fluid dynamics

This is the study of fluid in motion while considering the forces that cause the motion. The hydraulic/pneumatic pump is a typical example of fluid dynamics. Here we observe the mechanical force as well as the behavior of the fluid.

How Fluid Mechanics help us in our day to day life?

Fluids mechanics is an important part of most mechanical systems. Its knowledge will give you the holistic understanding. In general, it is about how we get the work done by providing energy to the fluids or how we convert fluid energy into other forms of energy.

  • Global transportation has benefited a lot from Fluid Mechanics. The understanding of lift and drag forces generated by the air over the wing of the aircraft led to the development of planes. Buoyancy forces helped us in developing sea-vessels, which play a major role in the inter-continental transport of goods. The understanding of the behavior of various combustible fluids (i.e. petrol and diesel) help us in designing the engines and intake/exhaust systems for automobiles.

    container ship fluid mechanics

    Buoyancy forces helped us in developing sea-vessels, which play a major role in the inter-continental transport of goods

  • Hydraulics and pneumatics is an important branch of fluid mechanics. Hydraulic systems offer the unique capability of providing high magnitude force per unit weight of the system. It has been used in aircraft for yaw and pitch control and also in the landing gear mechanism due to its lower weight. The pneumatic tools which work on compressed air are used for various applications ranging from screw-drivers to dental drills.
  • Lubrication is another important part of fluid mechanics. It studies the properties of fluid with respect to temperature. Therefore allowing us to minimize the friction between two moving parts and increase the efficiency of the system.
  • Fluid mechanics explains the behavior of various pumps. This helps when designing pumping systems for different applications ranging from home appliances to mud in oil drilling.
  • Heating, ventilation, and air-conditioning is an omnipresent application of fluid mechanics.

About: Darshak Parikh

M.Tech (Mechanical Engineering) from India’s prestigious Indian Institute of Technology (IIT), Gandhinagar with distinction. Darshak excels in Fluid Power (Hydraulics & Pneumatics) and Integrated Design and Manufacturing. Currently he is working as an R&D engineer at Mahindra & Mahindra Ltd (India’s giant automobile manufacturer).

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