Fluid Mechanics
Introduction
Fluid mechanics is the branch of physics that studies the behavior of fluids (liquids, gases, and plasmas) and the forces on them. It has applications in a wide range of disciplines, including mechanical, civil, chemical, and biomedical engineering, as well as in atmospheric science and planetary science.
Fundamentals of Fluid Mechanics
Fluid mechanics is based on the principles of conservation laws. These laws state that certain physical properties of an isolated physical system (such as mass, energy, or momentum) do not change over time.
Fluid Statics
Fluid statics, or hydrostatics, is the branch of fluid mechanics that studies fluids at rest. It encompasses the study of the conditions under which fluids are at rest in stable equilibrium. The use of fluid statics involves the calculation of the pressure in a fluid, or on the boundary of a closed container.
Fluid Dynamics
Fluid dynamics is the subdiscipline of fluid mechanics that deals with fluid flow—the science of liquids and gases in motion. This area of fluid mechanics is often divided into sub-disciplines including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion).
The Navier-Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, describe the motion of fluid substances. These equations arise from applying Newton's second law to fluid motion, together with the assumption that the stress in the fluid is the sum of a diffusing viscous term and a pressure term.
Applications of Fluid Mechanics
Fluid mechanics is used in a vast array 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.
