Fluid Dynamics

Fluid dynamics is "an area of applied science concerned with the movement of liquids and gases," according to the American Heritage Dictionary. Fluid dynamics is one of the two branches of fluid mechanics, which is the study of fluids and how their strength affects them. (The other category is fluid statics which deals with fluids at rest.)

Fluid Dynamics is a sub-discipline of fluid mechanics that deals with fluid movement in motion. There are several branches of fluid dynamics, aerodynamics, and hydrodynamics few in the popularly recognized fluid mechanics. This covers a wide variety of applications, such as calculating force & moments, determining the mass flow rate of oil through pipelines, forecasting weather patterns, understanding interstellar nebulae, and modeling.

Scientists in a variety of areas research fluid dynamics. Fluid dynamics offers tools to study the evolution of planets, ocean tides, weather patterns, plate tectonics, and also blood circulation. Some of the important technological applications of fluid dynamics include rocket engines, wind turbines, oil pipelines, and air conditioning systems.

What is Flow?

The movement of liquids and gases, in general, is referred to as "flow," a term that explains how fluids behave and how they interact with their natural environment. For example, water flowing through a canal or pipe or over a surface. Flow may be either slow or unstable. 

In his lecture on elementary fluid dynamics (University of Kentucky, 2009), J. M. McDonough, Professor of Engineering at the University of Kentucky, writes, "If all the properties of the flow are independent of time, the flow is constant; otherwise it is unsteady." That is, the steady flow does not change over time.

An example of steady flow will be the flow of water through the pipe at a constant rate. On the other side, a flood or stream from an old-fashioned hand pump is an example of a steady flow.

Flow can be either laminar or turbulent. The laminar flow is smoother, while the turbulent flow is more chaotic. One important factor in deciding the flow status of the fluid is its viscosity or thickness, where higher viscosity increases the propensity of the flow to be laminar. 

Patrick McMurtry, an engineering professor at the University of Utah, explains the difference in his online class notes, "Observations About Turbulent Flows" (University of Utah, 2000), writing, "By laminar flow, we are usually referring to a smooth, steady flow of fluid in which any caused disturbances are dampened by relatively strong viscous forces.

What are the Dynamics of Computational Fluid? 

Computational fluid dynamics is a fluid mechanics branch that uses numerical modeling and algorithms to solve and interpret fluid flow problems. High-speed supercomputers are used to measure what is needed to simulate the interaction of liquids and gases. 

Application of Fluid Mechanics 

Fluid Dynamics Can Be Seen in the Following Ways -

• Fluid dynamics is used to measure the forces acting on the aircraft. 

• This is used to track content flow levels, such as oil from pipelines. 

• This may also be used in traffic engineering (traffic viewed as a continuous flow of liquids).

Equations in Fluid Dynamics: Bernoulli’s Equation

\[= \frac{P}{\rho g} + z + \frac{v^{2}}{2g} = k\]

\[= \frac{P}{\rho g} +  \frac{v^{2}}{2g} = k\]

\[\frac{P}{\rho } + gz + \frac{v^{2}}{z} = k\]

\[\frac{P}{\rho g } + z + \frac{v^{2}}{2 g} = \frac{k}{g}\]

\[\frac{P}{\rho g } = \frac{v^{2}}{2g} + z = \frac{k}{g}\]

Here,

\[\frac{P}{\rho g } \]  is the pressure head or pressure energy per unit weight fluid

\[\frac{v^{2}}{2g}\] is the kinetic head or kinetic energy per unit weight

z is the potential head or potential energy per unit weight

P is the Pressure

\[\rho\] is the Density

K is the Constant

The Bernoulli equation is different for isothermal as well as adiabatic processes.

\[\frac{dp}{\rho } + VdV + gdZ = 0\]

\[\int (\frac{dp}{\rho} + VdV + gdZ) = K\]

\[\int \rho dp + V^{2}2 + gZ = K\]

Where,

Z is the elevation point

\[\rho\] is the density of the fluid

The equation can also be written as,

\[q+P=P_{0}\]

Where,

q is the dynamic pressure

\[P_{0}\] is the total pressure

P is the static pressure

Alternative Terms for Fluid Mechanics

Fluid dynamics is also often referred to as hydrodynamics, but this is more of a historical term. In the 20th century, the term "fluid dynamics" has been much more widely used. 

Technically, it would be more fitting to say that hydrodynamics is when fluid dynamics are applied to fluids in motion and aerodynamics when fluid dynamics are applied to gasses in motion. 

For action, however, advanced subjects such as hydrodynamic stability and magnetohydrodynamics use the "hydro-" suffix only when applying these definitions to the motion of gases.

Uses of Fluid Dynamics in Real Life

There are various applications of fluid dynamics in real life.

Here are some of the various ways in which fluid dynamics is applied in real life.

• Automobiles

Fluid is a crucial part of any automobile. Every automobile only runs when there is a fluid press. Fluid in automobiles is usually petrol or diesel, or any other roil. This fluid in an automobile is called fuel. The function of fuel is to lubricate the machine parts, generate power as well as cool the engine when it is heated due to various reasons. In automobiles like cars and other huge engines, water is used as a cooling fluid.

• Air Conditioners and Refrigerators

Water is used as the fluid in both air conditioners as well as refrigerators. The function of the water in an air conditioner is to absorb the heat in the room, and throw it in the atmosphere outside, and so is the case with refrigerators. The fluids transfer the heat from the high-temperature area to the low-temperature area. 

• Thermal Power Plants

Water is the main fluid used in thermal power plants. Thermal power plants generate electricity and to do so, water is heated in a boiler and is converted into hot steam that is then passed into the blades of a turbine. This produces electricity.

• Nuclear Power Plants

In nuclear power plants, water is used as both the working fluid and the coolant. In a few nuclear plants, the heart of the nuclear reactors isn't used to generate steam directly.

• Hydraulic Machines

The fluid is an important part of the hydraulic machines. The machines in which water or oil is used are known as hydraulic machines. These machines operate on water or oil. The fluids like water or oil have the capacity to lift extreme loads and exert pressure.

• Hydroelectric Power Plants

Water is used to generate electricity on a large scale. The water that is stored in the dam contains potential energy which is then released on the turbines that create electric energy. Hydroelectric energy is one of the major contributors to electricity in the world today.

Importance of Fluid Dynamics

Fluid dynamics is an integral part of physics. Fluid dynamics is important to learn and understand for various reasons. Fluid has immense power and can be used actively to create power.

As mentioned above, Fluids, when burnt, produce a lot of heat. This can be used for various applications. The usage of petrol or diesel in cars is one such example.

Some fluids have the capacity to exert immense pressure and have the ability to list tonnes of loads. Oils and water are some of the fluids that manage to do so. This can be seen in the application of hydraulic machines and hydraulic lifters.

The main feature of fluid is the ability to flow. This trait can be put to the best use in machines that need constant lubrication. Oils are a good example as it is used in various machines to lubricate the machine parts.

Water contains potential energy as well as kinetic energy that can be put to good use in the creation of electric energy. Fluids are versatile. Hence, the study of fluids is crucial to make use of their properties and create inventions that benefit mankind.

Conclusion

This is all about fluid dynamics, its important formulas, and its applications in the real world. Learn how this subject has a huge impact on modern-day operations with proper examples.