Fluid dynamics

Fluid dynamics is a sub-discipline of Fluid mechanics that deals with fluid flow—the natural science of fluids (liquids and gases) in motion. It has several sub-disciplines itself, including Aerodynamics (the study of air and other gases in motion) and Hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission in nuclear reactors.

Fundamental principles

Fluid dynamics is governed by two fundamental principles: Conservation of mass and Conservation of energy. The principle of conservation of mass states that the rate of change of mass in an isolated system is zero. The principle of conservation of energy, also known as the first law of thermodynamics, states that energy cannot be created or destroyed, only transferred or changed from one form to another.

Equations of fluid dynamics

The foundational axioms of fluid dynamics are the Navier-Stokes equations, a set of equations that describe the motion of fluid substances. These equations are based on the principles of conservation of momentum, conservation of mass, and conservation of energy. They can be simplified in a number of ways, all of which make them easier to solve. Some of the simplified forms include the Euler equations, Potential flow equation, and the Boundary layer equation.

Applications of fluid dynamics

Fluid dynamics is used in a wide variety of applications. Some of the most common include:

• Aerodynamics: The study of how gases interact with moving bodies. This is crucial in many fields, including aviation, automotive design, and meteorology.
• Hydrodynamics: The study of liquids in motion, with applications in areas such as naval architecture and marine engineering.
• Weather forecasting: Fluid dynamics is used to model the Earth's atmosphere and oceans, which are both fluid systems.
• Astrophysics: Many phenomena in the universe, from the formation of stars to the behavior of galaxies, can be understood through the principles of fluid dynamics.

See also

• Fluid statics
• Bernoulli's principle
• Reynolds number
• Laminar flow
• Turbulent flow