# Fluid Dynamics

## Article Summary & FAQs

### What is fluid dynamics?

In physics, fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow. Fluid dynamics is one of the most important of all areas of physics.

### Key Facts

• Conservation of mass in fluid dynamics states that all mass flow rates into a control volume are equal to all mass flow rates out of the control volume plus the rate of mass change within the control volume.
• Bernoulli’s equation can be considered a statement of the conservation of energy principle appropriate for flowing fluids.
• The Reynolds number is one of the characteristic numbers used for predicting whether a flow condition will be laminar or turbulent. It is defined as the ratio of inertial forces to viscous forces.
• Head loss of the hydraulic system is divided into two main categories:
• Darcy’s equation can be used to calculate major losses. The friction factor for fluid flow can be determined using a Moody chart.
• In fluid dynamicsdrag is a force acting opposite to the relative motion of any moving object. The force a flowing fluid exerts on a body in the flow direction.
• By definition, multiphase flow is the interactive flow of two or more distinct phases with common interfaces in, say, a conduit.
• Centrifugal pumps are devices that are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow.
What is difference between fluid mechanics and fluid dynamics?
What is the difference between fluid mechanics and fluid dynamics?

Fluid mechanics is the study of the forces on fluids. These fluids can be either gas or liquid. In physics, fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow. Fluid mechanics include fluid statics (the study of fluids at rest) and fluid dynamics (the study of fluids in motion).

What is the definition of fluid?
What is the definition of fluid?

In physics, a fluid is a substance that continually deforms (flows) under applied shear stress. The characteristic that distinguishes a fluid from a solid is its inability to resist deformation under applied shear stress (a tangential force per unit area). Fluids are a subset of the phases of matter and include liquids, gases, plasmas, and, to some extent, plastic solids.

What is fluid dynamics used for?
What is fluid dynamics used for?

Fluid dynamics are an important part of most industrial processes, especially those involving the
transfer of heat. In nuclear reactors, the heat removal from the reactor core is accomplished by passing a liquid or gaseous coolant through the core and other regions where heat is generated.

## Fluid Dynamics

In physics, fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow. Fluid dynamics is one of the most important of all areas of physics. Life as we know it would not exist without fluids and without the behavior that fluids exhibit. The air we breathe and the water we drink (which makes up most of our body mass) are fluids. Fluid dynamics has many applications, including calculating forces and moments on aircraft (aerodynamics) and determining water’s mass flow rate through pipelines (hydrodynamics).

Fluid dynamics are an important part of most industrial processes, especially those involving the
transfer of heat. In nuclear reactors, the heat removal from the reactor core is accomplished by passing a liquid or gaseous coolant through the core and other regions where heat is generated. The nature and operation of the coolant system are among the most important considerations in designing a nuclear reactor.

Fluid flow in the nuclear field can be complex and is not always subject to rigorous mathematical analysis. Unlike solids, the particles of fluids move through piping and components at different velocities and are often subjected to different accelerations. The foundational axioms of fluid dynamics are the conservation laws, specifically, conservation of mass (leading to the continuity equation), conservation of linear momentum, and conservation of energy.

References:
Reactor Physics and Thermal Hydraulics:
1. J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
2. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
3. W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
4. Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317
5. Todreas Neil E., Kazimi Mujid S. Nuclear Systems Volume I: Thermal Hydraulic Fundamentals, Second Edition. CRC Press; 2 edition, 2012, ISBN: 978-0415802871
6. Zohuri B., McDaniel P. Thermodynamics in Nuclear Power Plant Systems. Springer; 2015, ISBN: 978-3-319-13419-2
7. Moran Michal J., Shapiro Howard N. Fundamentals of Engineering Thermodynamics, Fifth Edition, John Wiley & Sons, 2006, ISBN: 978-0-470-03037-0
8. Kleinstreuer C. Modern Fluid Dynamics. Springer, 2010, ISBN 978-1-4020-8670-0.
9. U.S. Department of Energy, THERMODYNAMICS, HEAT TRANSFER, AND FLUID FLOW. DOE Fundamentals Handbook, Volume 1, 2 and 3. June 1992.

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