A Summary Explanation of Fluid Mechanics In Engineering

A Summary Explanation of Fluid Mechanics In Engineering

When mechanical engineering is mentioned in a conversation, people without any prior knowledge will imagine solid systems such as gears. But fluids are also very important in mechanical engineering and lots of engineering systems. We will explain this importance as a summary here. 

What Is Fluid?

As we know that there are three main phases of substances; gas, liquid and solid. There are lots of kinds of engineering systems that utilize these three phases separately or at the same time. In the engineering approach, solid and fluid systems are separated from each other. Here, fluid include the liquid and gas phases of substance. They are of fluid mechanics deals with the natural rules and applications of these natural rules of fluids to useful systems. 

Schaum’s Outline of Fluid Mechanics and Hydraulics (Schaum’s)

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Better Understanding of Fluid Mechanics

In mechanics, solid bodies are aforementioned. If a mechanical system is stationary, the system is referred to as static. And the branch of mechanics that deals with static systems is called statics. On the other hand, if a mechanical system has moving parts or dynamic parts, a branch of mechanics called dynamics deals with these systems. 

As you understand that, the other part of mechanics is fluid mechanics. If a fluid is stationary, fluid statics deals with these systems. And if fluid is moving, this is called fluid dynamics. 

First of all, you need to know the distinction between the mechanics and fluid mechanics, before starting fluid mechanics. 

Some Subcategories of Fluid Mechanics

Gas turbine(Image Source:https://www.flickr.com/photos/[email protected]/4111637703).

According to the application areas and useful systems of fluid mechanics, fluid mechanics have various sub-categories. 

According to the compressibilities of moving fluids, fluids are classified as compressible or incompressible. The sub-category of fluid mechanics which is called hydrodynamics deals with the incompressible dynamic fluid systems. The sub-category hydrodynamics which is also called hydraulics deals with the liquid flows in pipes and channels. A very known example of hydraulics is dozer bucket mechanisms. There are very complex hydraulic mechanisms to operate these bucket mechanisms. 

Compressible fluid means that if a fluid undergoes significant density changes. A sub-category of fluid mechanics deals with these compressible systems, called gas dynamics. There are lots of engineering systems that include the flow of fluids through nozzles at a very high speed, which undergoes very high-density changes. The flow of burnt gases through jet engine nozzles is a very important example of it. 

Engineering Applications Include Fluid Mechanics

Fluid Mechanics DeMYSTiFied

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Fluid mechanics deal with the characteristics and behavior of fluids with the effect of different external factors. With the consideration of these different external factors, the intended fluid and engineering system can be obtained with fluid mechanics. Let’s take a look at some application areas of fluid mechanics. 

Human Body

Heart and vein system(Image Source:https://my.clevelandclinic.org/health/articles/17061-blood-vessels-illustrations)

The human body contains nearly 70% of the fluid. So, fluid mechanisms are very important in our body to stay healthy. The most important fluid system is the blood, heart, and vein system. The heart pumps the blood through veins to organs. The mechanism can seem easy. But it is not. the pressure in our veins, the flow regime of blood in our veins, the physical properties of our blood for healthy flow in our veins must be in specific ranges. So, a special design according to the fluid mechanics is required to obtain such a system like this. 

Water, Natural Gas, Sewage Piping Systems

There are lots of kinds of piping and duct systems around us in our buildings to carry on the civilized society. Flowing water from our taps, natural gas that warms up us, sewage systems that we can repel the dirt from our homes are designed according to the fluid mechanics fundamentals. Without the precise calculations of fluid mechanics, we can not have well-working systems like them. 

Refrigerators, Heat Exchangers…

There is a special fluid which is called the refrigerant in refrigerators and in air conditioning systems. This refrigerant absorbs heat from the inside of the refrigerator and rejects that heat at the outside of the refrigerator owing to the specially designed compressor and valve systems in terms of fluid mechanics. 

Heat exchangers are also very important systems that include lots of piping and pump systems which are designed according to the fluid mechanics fundamentals. 


Automobile fuel supply system(Source:https://www.ingenieriaymecanicaautomotriz.com/fuel-system-components-working-principles-symptoms-and-emission-controls/).

If you take a look at the fuel supply systems of automobiles, you can see that fluid mechanics fundamentals are intensely used. From the fuel tank to engine cylinders, you need to supply the air-fuel mixture at specific rates in which the fluid mechanics fundamentals must be adopted. 


For planes, rockets, and automobiles, the design of precise aerodynamics is very important to obtain fuel-efficient and advanced technologies. Aerodynamics is directly related to fluid mechanics fundamentals. 


This small explanation of fluid mechanics in mechanical engineering will be very vital before starting everything. 

Do not forget to leave your comments and questions below about the fluid mechanics in mechanical engineering! 

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